Recombinant vesiculoviruses and their uses

ABSTRACT

The present invention provides recombinant replicable vesiculoviruses. The invention provides a method which, for the first time, successfully allows the production and recovery of replicable vesiculoviruses, as well as recombinant replicable vesiculoviruses, from cloned DNA, by a method comprising expression of the full-length positive-strand vesiculovirus antigenomic RNA in host cells. The recombinant vesiculoviruses do not cause serious pathology in humans, can be obtained in high titers, and have use as vaccines. The recombinant vesiculoviruses can also be inactivated for use as killed vaccines.

This invention was made with government support under grant number R37 AI243245 awarded by the National Institutes of Health. The government has certain rights in the invention.

1. INTRODUCTION

The present invention relates to recombinant vesiculoviruses which are replicable and capable of expressing foreign nucleic acid contained in their genome. Also provided are inactivated forms of the recombinant viruses. The vesiculoviruses are useful in vaccine formulations to prevent or treat various diseases and disorders.

2. BACKGROUND OF THE INVENTION 2.1. Rhabdoviruses

Rhabdoviruses are membrane-enveloped viruses that are widely distributed in nature where they infect vertebrates, invertebrates, and plants. There are two distinct genera within the rhabdoviruses, the Lyssavirus genus and the Vesiculovirus genus. Rhabdoviruses have single, negative-strand RNA genomes of 11-12,000 nucleotides (Rose and Schubert, 1987, Rhabdovirus genomes and their products, in The Viruses: The Rhabdoviruses, Plenum Publishing Corp., NY, pp. 129-166). The virus particles contain a helical, nucleocapsid core composed of the genomic RNA and protein. Generally, three proteins, termed N (nucleocapsid), P (formerly termed NS, originally indicating nonstructural), and L (large) are found to be associated with the nucleocapsid. An additional matrix (M) protein lies within the membrane envelope, perhaps interacting both with the membrane and the nucleocapsid core. A single glycoprotein (G) species spans the membrane and forms the spikes on the surface of the virus particle. Because the genome is the negative sense [i.e., complementary to the RNA sequence (positive sense) that functions as mRNA to directly produce encoded protein], rhabdoviruses must encode and package an RNA-dependent RNA polymerase in the virion (Baltimore et al., 1970, Proc. Natl. Acad. Sci. USA 66: 572-576), composed of the P and L proteins. This enzyme transcribes genomic RNA to make subgenomic MRNAS encoding the 5-6 viral proteins and also replicates full-length positive and negative sense RNAs. The genes are transcribed sequentially, starting at the 3′ end of the genomes. The same basic genetic system is also employed by the paramyxoviruses and filoviruses.

The prototype rhabdovirus, vesicular stomatitis virus (VSV), grows to very high titers in most animal cells and can be prepared in large quantities. As a result, VSV has been widely used as a model system for studying the replication and assembly of enveloped RNA viruses. The study of VSV and related negative strand viruses has been limited by the inability to perform direct genetic manipulation of the virus using recombinant DNA technology. The difficulty in generating VSV from DNA is that neither the full-length genomic nor antigenomic RNAs are infectious. The minimal infectious unit is the genomic RNA tightly bound to 1,250 subunits of the nucleocapsid (N) protein (Thomas et al., 1985, J. Virol. 54:598-607) and smaller amounts of the two virally encoded polymerase subunits, L and P. To reconstitute infectious virus from the viral RNA, it is necessary first to assemble the N protein-RNA complex that serves as the template for transcription and replication by the VSV polymerase. Although smaller negative-strand RNA segments of the influenza virus genome can be packaged into nucleocapsids in vitro, and then rescued in influenza infected cells (Enami et al., 1990, Proc. Natl. Acad. Sci. USA 87:3802-3805; Luytjes et al., 1989, Cell 59:1107-1113), systems for packaging the much larger rhabdoviral genomic RNAs in vitro are not yet available.

Recently, systems for replication and transcription of DNA-derived minigenomes or small defective RNAs from rhabdoviruses (Conzelmann and Schnell, 1994, J. Virol. 68:713-719; Pattnaik et al., 1992, Cell 69:1011-1120) and paramyxoviruses (Calain et al., 1992, Virology 191:62-71; Collins et al., 1991, Proc. Natl. Acad. Sci. USA 88:9663-9667; Collins et al., 1993, Virology 195:252-256; De and Banerjee, 1993, Virology 196:344-348; Dimock and Collins, 1993, J. Virol. 67:2772-2778; Park et al., 1991, Proc. Natl. Acad. Sci. USA 88:5537-5541) have been described. In these systems, RNAs are assembled into nucleocapsids within cells that express the viral N protein and polymerase proteins. Although these systems have been very useful, they do not allow genetic manipulation of the full-length genome of infectious viruses.

The recovery of rabies virus from a complete cDNA clone was published recently (Schnell et al., 1994, EMBO J. 13:4195-4203). The infectious cycle was initiated by expressing the antigenomic (full-length positive strand) RNA in cells expressing the viral N, P, and L proteins. Although rabies virus is a rhabdovirus, it is structurally and functionally different from the vesiculoviruses. Rabies virus is a Lyssavirus, not a Vesiculovirus. Lyssaviruses invade the central nervous system. Vesiculoviruses invade epithelial cells, predominantly those of the tongue, to produce vesicles. Rabies virus causes encephalitis in a variety of animals and in humans, while VSV causes an epidemic but self-limiting disease in cattle. In sharp contrast to VSV-infected cells, rabies virus produces little or no cytopathic effect in infected cell culture, replicates less efficiently than VSV in cell culture, and causes little depression of cellular DNA, RNA or protein synthesis in infected cell cultures (see Baer et al., 1990, in Virology, 2d ed., Fields et al. (eds.), Raven Press, Ltd., NY, pp. 883, 887). Indeed, there is no cross-hybridization observed between the genomes of rabies virus and VSV, and sequence homology between the two genomes is generally discernable only with the aid of computer run homology programs. The differences between vesiculoviruses and rabies virus, and the extremely rare nature of rabies virus recovery from cDNA (˜10⁸ cells are transfected to yield one infectious cell), renders it unpredictable whether the strategy used with rabies virus would be successful for viruses of a different genus, i.e., the vesiculoviruses.

The recovery of infectious measles virus, another negative strand RNA virus, from cloned cDNA has been attempted, without success (see Ballart et al., 1990, EMBO J. 9(2):379-384 and the retraction thereof by Eschle et al., 1991, EMBO J. 10(11):3558).

2.2. Vaccines

The development of vaccines for the prevention of viral, bacterial, or parasitic diseases is the focus of much research effort.

Traditional ways of preparing vaccines include the use of inactivated or attenuated pathogens. A suitable inactivation of the pathogenic microorganism renders it harmless as a biological agent but does not destroy its immunogenicity. Injection of these “killed” particles into a host will then elicit an immune response capable of preventing a future infection with a live microorganism. However, a major concern in the use of killed vaccines (using inactivated pathogen) is failure to inactivate all the microorganism particles. Even when this is accomplished, since killed pathogens do not multiply in their host, or for other unknown reasons, the immunity achieved is often incomplete, short lived and requires multiple immunizations. Finally, the inactivation process may alter the microorganism's antigens, rendering them less effective as immunogens.

Attenuation refers to the production of strains of pathogenic microorganisms which have essentially lost their disease-producing ability. One way to accomplish this is to subject the microorganism to unusual growth conditions and/or frequent passage in cell culture. Mutants are then selected which have lost virulence but yet are capable of eliciting an immune response. Attenuated pathogens often make good immunogens as they actually replicate in the host cell and elicit long lasting immunity. However, several problems are encountered with the use of live vaccines, the most worrisome being insufficient attenuation and the risk of reversion to virulence.

An alternative to the above methods is the use of subunit vaccines. This involves immunization only with those components which contain the relevant immunological material.

Vaccines are often formulated and inoculated with various adjuvants. The adjuvants aid in attaining a more durable and higher level of immunity using small amounts of antigen or fewer doses than if the immunogen were administered alone. The mechanism of adjuvant action is complex and not completely understood. However, it may involve the stimulation of cytokine production, phagocytosis and other activities of the reticuloendothelial system as well as a delayed release and degradation of the antigen. Examples of adjuvants include Freund's adjuvant (complete or incomplete), Adjuvant 65 (containing peanut oil, mannide monooleate and aluminum monostearate), the pluronic polyol L-121, Avridine, and mineral gels such as aluminum hydroxide, aluminum phosphate, etc. Freund's adjuvant is no longer used in vaccine formulations for humans because it contains nonmetabolizable mineral oil and is a potential carcinogen.

3. SUMMARY OF THE INVENTION

The present invention provides recombinant replicable vesiculoviruses. The prior art has unsuccessfully attempted to produce replicable vesiculoviruses from cloned DNA. In contrast, the invention provides a method which, for the first time, has successfully allowed the production and recovery of replicable vesiculoviruses, as well as recombinant replicable vesiculoviruses, from cloned DNA.

The vesiculoviruses of the invention are produced by providing in an appropriate host cell: (a) DNA that can be transcribed to yield (encodes) vesiculovirus antigenomic (+) RNA (complementary to the vesiculovirus genome), (b) a recombinant source of vesiculovirus N protein, (c) a recombinant source of vesiculovirus P protein, and (d) a recombinant source of vesiculovirus L protein; under conditions such that the DNA is transcribed to produce the antigenomic RNA, and a vesiculovirus is produced that contains genomic RNA complementary to the antigenomic RNA produced from the DNA.

The invention provides an infectious recombinant vesiculovirus capable of replication in an animal into which the recombinant vesiculovirus is introduced, in which the genome of the vesiculovirus comprises foreign RNA which is not naturally a part of the vesiculovirus genome. The recombinant vesiculovirus is formed by producing vesiculoviruses according to the method of the invention, in which regions of the DNA encoding vesiculovirus antigenomic (+) RNA that are nonessential for viral replication have been inserted into or replaced with foreign DNA.

In a preferred embodiment, the foreign RNA contained within the genome of the recombinant vesiculovirus (originally encoded by the foreign DNA), upon expression in an appropriate host cell, produces a protein or peptide that is antigenic or immunogenic.

The recombinant vesiculoviruses of the invention have use as vaccines. In one embodiment, where the foreign RNA directs production of an antigen that induces an immune response against a pathogen, the vaccines of the invention have use in the treatment or prevention of infections by such a pathogen (particularly a pathogenic microorganism), and its clinical manifestations, i.e., infectious disease. In a preferred embodiment, such an antigen displays the antigenicity or immunogenicity of an envelope glycoprotein of a virus other than a vesiculovirus, and the antigen is incorporated into the vesiculovirus envelope. The recombinant vesiculoviruses also have uses in diagnosis, and monitoring progression of infectious disorders, including response to vaccination and/or therapy.

In another embodiment, where the foreign RNA directs production of an antigen that induces an immune response against a tumor, the recombinant viruses of the invention have uses in cancer immunoprophylaxis, immunotherapy, and diagnosis, and monitoring of tumor progression or regression.

The recombinant vesiculoviruses can be used as live vaccines, or can be inactivated for use as killed vaccines. The recombinant viruses can also be used to produce large quantities of readily purified antigen, e.g., for use in subunit vaccines.

The invention also provides vaccine formulations, kits, and recombinant host cells.

4. DESCRIPTION OF THE FIGURES

FIG. 1. Nucleotide sequence of plasmid pVSVFL(+), showing the complete DNA sequence that is transcribed to produce VSV antigenomic (+) RNA, and predicted sequences of the encoded VSV proteins. [N protein: SEQ ID NO:2; P protein: SEQ ID NO:3; M protein: SEQ ID NO:4; G protein: SEQ ID NO:S; L protein: SEQ ID NO:6] The noncoding and intergenic regions are observable. The upper line of sequence (SEQ ID NO:1) is the VSV antigenomic positive strand; lower line=SEQ ID NO:7. Restriction sites are indicated. The transmembrane and cytoplasmic domains of the G protein are also indicated. The sequences of the first T7 RNA polymerase promoter (SEQ ID NO:8), the second T7 RNA polymerase promoter (SEQ ID NO:9); leader sequence (SEQ ID NO:10), T7 RNA polymerase transcription termination signal (SEQ ID NO:11), and the sequence that is transcribed to produce the HDV ribozyme (SEQ ID NO:12) are shown.

FIG. 2. Nucleotide sequence of a portion of plasmid pVSVSS1, showing the synthetic DNA insert containing the polylinker region inserted between the G and L coding regions (3′ of G and 5′ of L) containing unique restriction enzyme recognition sites, namely, XmaI, NotI, and SmaI. Upper line of sequence: SEQ ID NO:13; lower line of sequence: SEQ ID NO:14.

FIG. 3. Gene junctions of VSV. The nucleotide sequences at the 3′ end of the leader RNA and the 5′ and 3′ ends of each mRNA are shown along with the corresponding genomic sequences (vRNA) (SEQ ID NO:15-31). The intergenic dinucleotides are indicated by bold letters. From Rose and Schubert, 1987, in The Viruses: The Rhabdoviruses, Plenum Press, NY, pp. 129-166, at p. 136.

FIG. 4. Plasmid DNA construction. A. The diagram illustrates the cloned VSV genomic sequence and the four DNA fragments (numbered 1-4) that were used to generate the plasmid pVSVFL(+). The horizontal arrows represent PCR primers used to generate fragments 1 and 3. B. Diagram of the plasmid pVSVFL(+) that gives rise to infectious VSV. The locations of the VSV genes encoding the five proteins N, P, M, G, and L are shown. The stippled region from Sac I to Xho I represents the pBSSK⁺ vector sequence, and the hatched segments represent the regions of the VSV genome generated by PCR. Transcription from the T7 promoter generates the complete (+) strand VSV RNA.

FIG. 5. Proteins present in wild-type and recombinant VSVs. Proteins from 1% of the virus recovered from approximately 5×10⁶ infected BHK cells were separated by SDS-PAGE (10% acrylamide) and visualized by staining with Coomassie brilliant blue. Positions of the five VSV proteins are indicated.

FIG. 6. Identification of a restriction enzyme recognition sequence in the recombinant VSV. A 620 nucleotide segment of genomic RNA isolated from wildtype and recombinant VSV was amplified by reverse transcription and PCR using the primers 5′-CATTCAAGACGCTGCTTCGCAACTTCC (SEQ ID NO:32) and 5′-CATGAATGTTAACATCTCAAGA (SEQ ID NO:33). Controls in which reverse transcriptase was omitted from the reaction are indicated. DNA samples were either digested with Nhe I or left undigested prior to electrophoresis on a 6% polyacrylamide gel as indicated. DNA was detected by staining with ethidium bromide. Sizes of DNA markers are indicated on the left.

FIG. 7. Autoradiogram showing the sequence of genomic RNA from recombinant VSV. RNA prepared from recombinant VSV was sequenced by the dideoxy method using reverse transcriptase. The written sequence corresponds to nucleotides 1563-1593 in the G mRNA (Rose and Gallione, 1981, J. Virol. 39:519-528). The underlined sequence represents the four nucleotides that were changed to generate the Nhe I site.

FIG. 8. Protein analysis of recombinant VSV expressing the glycoprotein from the New Jersey serotype. Proteins from 1% of the virus pelleted from the medium of approximately 5×10⁶ BHK cells infected for 24 hours with wildtype VSV_(I) (lane 1), recombinant VSV_(I/NJG) (lane 2) or wildtype VSV_(NJ) (lane 3) were separated by SDS-PAGE (10% acrylamide). The proteins were visualized by staining with Coomassie brilliant blue. Positions of viral proteins are indicated.

5. DETAILED DESCRIPTION OF THE INVENTION

The present invention provides recombinant replicable vesiculoviruses. The prior art has unsuccessfully attempted to produce replicable vesiculoviruses from cloned DNA. In contrast, the invention provides a method which, for the first time, has successfully allowed the production and recovery of replicable vesiculoviruses, as well as recombinant replicable vesiculoviruses, from cloned DNA. Expression of the full-length positive-strand vesiculovirus RNA in host cells has successfully allowed the generation of recombinant vesiculoviruses from DNA, providing recombinant viruses that do not cause serious pathology in humans and that can be obtained in high titers, that have use as vaccines.

The vesiculoviruses of the invention are produced by providing in an appropriate host cell: (a) DNA that can be transcribed to yield (encodes) vesiculovirus antigenomic (+) RNA (complementary to the vesiculovirus genome), (b) a recombinant source of vesiculovirus N protein, (c) a recombinant source of vesiculovirus P protein, and (d) a recombinant source of vesiculovirus L protein; under conditions such that the DNA is transcribed to produce the antigenomic RNA, and a vesiculovirus is produced that contains genomic RNA complementary to the antigenomic RNA produced from the DNA.

The invention provides an infectious recombinant vesiculovirus capable of replication in an animal into which the recombinant vesiculovirus is introduced, in which the genome of the vesiculovirus comprises foreign RNA which is not naturally a part of the vesiculovirus genome. The recombinant vesiculovirus is formed by producing vesiculoviruses according to the method of the invention, in which regions of the DNA encoding vesiculovirus antigenomic (+) RNA that are nonessential for viral replication have been inserted into or replaced with foreign DNA.

Since the viruses are replicable (i.e., not replication-defective), they encode all the vesiculovirus machinery necessary for replication in a cell upon infection by the virus.

In a preferred embodiment, the recombinant vesiculovirus is a recombinant vesicular stomatitis virus (VSV).

In another preferred embodiment, the foreign RNA contained within the genome of the recombinant vesiculovirus (originally encoded by the foreign DNA), upon expression in an appropriate host cell, produces a protein or peptide that is antigenic or immunogenic. Such an antigenic or immunogenic protein or peptide whose expression is directed by the foreign RNA (present in the negative sense) within the vesiculovirus genome (by expression from the (+) antigenomic message) shall be referred to hereinafter as the “Antigen.” Appropriate Antigens include but are not limited to known antigens of pathogenic microorganisms or of tumors, as well as fragments or derivatives of such antigens displaying the antigenicity or immunogenicity of such antigens. A protein displays the antigenicity of an antigen when the protein is capable of being immunospecifically bound by an antibody to the antigen. A protein displays the immunogenicity of an antigen when it elicits an immune response to the antigen (e.g., when immunization with the protein elicits production of an antibody that immunospecifically binds the antigen or elicits a cell-mediated immune response directed against the antigen).

The recombinant vesiculoviruses of the invention have use as vaccines. In one embodiment, where the foreign RNA directs production of an Antigen (originally encoded by the foreign DNA used to produce the recombinant vesiculovirus or its predecessor) that induces an immune response against a pathogen, the vaccines of the invention have use in the treatment or prevention of infections by such a pathogen (particularly a pathogenic microorganism), and its clinical manifestations, i.e., infectious disease. The invention thus provides methods of prevention or treatment of infection and infectious disease comprising administering to a subject in which such treatment or prevention is desired one or more of the recombinant vesiculoviruses of the invention. The recombinant vesiculoviruses also have uses in diagnosis, and monitoring progression of infectious disorders, including response to vaccination and/or therapy.

In another embodiment, where the Antigen induces an immune response against a tumor, the recombinant viruses of the invention have uses in cancer immunoprophylaxis, immunotherapy, and diagnosis, and monitoring of tumor progression or regression.

The recombinant vesiculoviruses can be used as live vaccines, or can be inactivated for use as killed vaccines. The recombinant viruses can also be used to produce large quantities of readily purified antigen, e.g., for use in subunit vaccines.

In a specific embodiment, the foreign DNA used initially for production of the recombinant vesiculoviruses can also comprise a sequence encoding a detectable marker, e.g., β-galactosidase, β-glucuronidase, β-geo (Friedrich & Soriano, 1991, Genes Dev. 5:1513-1523).

In another specific embodiment, the foreign DNA can also comprise a sequence encoding a cytokine capable of stimulating an immune response. Such cytokines include but are not limited to, interleukin-2, interleukin-6, interleukin-12, interferons, and granulocyte-macrophage colony stimulating factors.

In a preferred aspect, upon infection with a recombinant vesiculovirus of the invention, the Antigen is expressed as a nonfusion protein. In a less preferred embodiment, the Antigen is expressed as a fusion protein, e.g., to the viral G protein. “Fusion protein,” as used herein, refers to a protein comprising an amino acid sequence from a first protein covalently linked via a peptide bond at its carboxy terminus to the amino terminus of an amino acid sequence from a second, different protein.

In one embodiment, a vaccine formulation of the invention contains a single type of recombinant vesiculovirus of the invention. In another embodiment, a vaccine formulation comprises a mixture of two or more recombinant viruses of the invention.

The vaccine formulations of the invention provide one or more of the following benefits: stability for long periods without refrigeration; ease of production; low cost and high titer of production; ability to be administered by local workers without advanced medical training; and involving administration of a microorganism that is known not to cause serious disease in humans.

The present invention also provides a host cell infected with a recombinant vesiculovirus capable of replication. In one embodiment, the host cell is a mammalian cell. Preferably, the mammalian cell is a hamster kidney cell.

5.1. DNA That can be Transcribed to Produce Vesiculovirus Antigenomic (+) RNA

Many vesiculoviruses are known in the art and can be made recombinant according to the methods of the invention. Examples of such vesiculoviruses are listed in Table I. TABLE I MEMBERS OF THE VESICULOVIRUS GENUS Virus Source of virus in nature VSV-New Jersey Mammals, mosquitoes, midges, blackflies, houseflies VSV-Indiana Mammals, mosquitoes, sandflies Alagoas Mammals, sandflies Cocal Mammals, mosquitoes, mites Jurona Mosquitoes Carajas Sandflies Maraba Sandflies Piry Mammals Calchaqui Mosquitoes Yug Bogdanovac Sandflies Isfahan Sandflies, ticks Chandipura Mammals, sandflies Perinct Mosquitoes, sandflies Porton-S Mosquitoes

Any DNA that can be transcribed to produce vesiculovirus antigenomic (+) RNA (complementary to the VSV genome) can be used for the construction of a recombinant DNA containing foreign DNA encoding an Antigen, for use in producing the recombinant vesiculoviruses of the invention. DNA that can be transcribed to produce vesiculovirus antigenomic (+) RNA (such DNA being referred to herein as “vesiculovirus (−) DNA”) is available in the art and/or can be obtained by standard methods. In particular, plasmid pVSVFL(+), containing VSV (−) DNA that is preferred for use in the present invention, has been deposited with the ATCC and assigned accession no. ______. In a preferred aspect, DNA that can be transcribed to produce VSV (+) RNA, [i.e., VSV (−) DNA], is used. VSV (−) DNA for any serotype or strain known in the art, e.g., the New Jersey or Indiana serotypes of VSV, can be used. The complete nucleotide and deduced protein sequence of the VSV genome is known, and is available as Genbank VSVCG, Accession No. J02428; NCBI Seq ID 335873; and is published in Rose and Schubert, 1987, in The Viruses: The Rhabdoviruses, Plenum Press, NY, pp. 129-166. Partial sequences of other vesiculovirus genomes have been published and are available in the art. The complete sequence of the VSV(−) DNA that is used in a preferred embodiment is contained in plasmid pVSVFL(+) and is shown in FIG. 1; also shown are with the predicted sequences of the VSV proteins (this sequence contains several sequence corrections relative to that obtainable from Genbank). Vesiculovirus (−) DNA, if not already available, can be prepared by standard methods, as follows: If vesiculoviral cDNA is not already available, vesiculovirus genomic RNA can be purified from virus preparations, and reverse transcription with long distance polymerase chain reaction used to generate the vesiculovirus (−) DNA. Alternatively, after purification of genomic RNA, VSV mRNA can be synthesized in vitro, and cDNA prepared by standard methods, followed by insertion into cloning vectors (see, e.g., Rose and Gallione, 1981, J. Virol. 39(2):519-528). Individual cDNA clones of vesiculovirus RNA can be joined by use of small DNA fragments covering the gene junctions, generated by use of reverse transcription and polymerase chain reaction (RT-PCR) (Mullis and Faloona, 1987, Meth. Enzymol. 155:335-350) from VSV genomic RNA (see Section 6, infra). Vesiculoviruses are available in the art. For example, VSV can be obtained from the American Type Culture Collection.

In a preferred embodiment, one or more, preferably unique, restriction sites (e.g., in a polylinker) are introduced into the vesiculovirus (−) DNA, in intergenic regions, or 5′ of the sequence complementary to the 3′ end of the vesiculovirus genome, or 3′ of the sequence complementary to the 5′ end of the vesiculovirus genome, to facilitate insertion of the foreign DNA.

In a preferred method of the invention, the vesiculovirus (−) DNA is constructed so as to have a promoter operatively linked thereto. The promoter should be capable of initiating transcription of the (−) DNA in an animal or insect cell in which it is desired to produce the recombinant vesiculovirus. Promoters which may be used include, but are not limited to, the SV40 early promoter region (Bernoist and Chambon, 1981, Nature 290:304-310), the promoter contained in the 3′ long terminal repeat of Rous sarcoma virus (Yamamoto, et al., 1980, Cell 22:787-797), the herpes thymidine kinase promoter (Wagner et al., 1981, Proc. Natl. Acad. Sci. U.S.A. 78:1441-1445), the regulatory sequences of the metallothionein gene (Brinster et al., 1982, Nature 296:39-42); heat shock promoters (e.g., hsp70 for use in Drosophila S2 cells); the ADC (alcohol dehydrogenase) promoter, PGK (phosphoglycerol kinase) promoter, alkaline phosphatase promoter, and the following animal transcriptional control regions, which exhibit tissue specificity and have been utilized in transgenic animals: elastase I gene control region which is active in pancreatic acinar cells (Swift et al., 1984, Cell 38:639-646; Ornitz et al., 1986, Cold Spring Harbor Symp. Quant. Biol. 50:399-409; MacDonald, 1987, Hepatology 7:425-515); insulin gene control region which is active in pancreatic beta cells (Hanahan, 1985, Nature 315:115-122), immunoglobulin gene control region which is active in lymphoid cells (Grosschedl et al., 1984, Cell 38:647-658; Adames et al., 1985, Nature 318:533-538; Alexander et al., 1987, Mol. Cell. Biol. 7:1436-1444), mouse mammary tumor virus control region which is active in testicular, breast, lymphoid and mast cells (Leder et al., 1986, Cell 45:485-495), albumin gene control region which is active in liver (Pinkert et al., 1987, Genes and Devel. 1:268-276), alpha-fetoprotein gene control region which is active in liver (Krumlauf et al., 1985, Mol. Cell. Biol. 5:1639-1648; Hammer et al., 1987, Science 235:53-58; alpha 1-antitrypsin gene control region which is active in the liver (Kelsey et al., 1987, Genes and Devel. 1:161-171), beta-globin gene control region which is active in myeloid cells (Mogram et al., 1985, Nature 315:338-340; Kollias et al., 1986, Cell 46:89-94; myelin basic protein gene control region which is active in oligodendrocyte cells in the brain (Readhead et al., 1987, Cell 48:703-712); and myosin light chain-2 gene control region which is active in skeletal muscle (Sani, 1985, Nature 314:283-286). Preferably, the promoter is an RNA polymerase promoter, preferably a bacteriophage or viral or insect RNA polymerase promoter, including but not limited to the promoters for T7 RNA polymerase, SP6 RNA polymerase, and T3 RNA polymerase. If an RNA polymerase promoter is used in which the RNA polymerase is not endogenously produced by the host cell in which it is desired to produce the recombinant vesiculovirus, a recombinant source of the RNA polymerase must also be provided in the host cell.

The vesiculovirus (−) DNA can be operably linked to a promoter before or after insertion of foreign DNA encoding an Antigen. Preferably, a transcriptional terminator is situated downstream of the vesiculovirus (−) DNA.

In another preferred embodiment, a DNA sequence that can be transcribed to produce a ribozyme sequence is situated at the immediate 3′ end of the vesiculovirus (−) DNA, prior to the transcriptional termination signal, so that upon transcription a self-cleaving ribozyme sequence is produced at the 3′ end of the antigenomic RNA, which ribozyme sequence will autolytically cleave (after a U) this fusion transcript to release the exact 3′ end of the vesiculovirus antigenomic (+) RNA. Any ribozyme sequence known in the art may be used, as long as the correct sequence is recognized and cleaved. (It is noted that hammerhead ribozyme is probably not suitable for use.) In a preferred aspect, hepatitis delta virus (HDV) ribozyme is used (Perrotta and Been, 1991, Nature 350:434-436; Pattnaik et al., 1992, Cell 69:1011-1020).

A preferred VSV(−) DNA for use, for insertion of foreign DNA, is that shown in FIG. 1 and contained in plasmid pVSVFL(+), in which a T7 RNA polymerase promoter is present 5′ of the sequence complementary to the 3′ end of the VSV genome. Plasmid pVSVFL(+) thus comprises (in 5′ to 3′ order) the following operably linked components: the T7 RNA polymerase promoter, VSV (−) DNA, a DNA sequence that is transcribed to produce an HDV ribozyme sequence (immediately downstream of the VSV (−) DNA), and a T7 RNA polymerase transcription termination site. A plasmid that can also be made and used is plasmid pVSVSS1, a portion of the sequence of which is shown in FIG. 2, in which a synthetic DNA polylinker, facilitating insertion of foreign DNA, has been inserted into pVSVFL(+) between the G and L coding regions. The polylinker was synthesized on a DNA synthesizer so as to have ends compatible for ligation into an NheI site, and to contain the unique restriction enzyme recognition sites XmaI, SmaI, and NotI, facilitating insertion of foreign DNA generated by cleavage with one of these enzymes or ligated to a linker containing a recognition site for one of these enzymes (which is then subjected to cleavage prior to insertion).

The foreign DNA encoding an Antigen is inserted into any region, or replaces any region, of the vesiculovirus (−) DNA that is not essential for vesiculovirus replication. In a preferred embodiment, the foreign DNA is thus inserted into an intergenic region, or a portion of the vesiculovirus (−) DNA that is transcribed to form the noncoding region of a viral mRNA. In a preferred embodiment, the invention provides a nucleic acid comprising the DNA sequence of plasmid pVSVFL(+) as depicted in FIG. 1 from nucleotide numbers 623-12088 (a portion of SEQ ID NO:1), in which a region nonessential for vesiculovirus replication has been inserted into or replaced by foreign DNA.

Vesiculoviruses have a defined intergenic structure. Extensive homologies are found around the intergenic dinucleotides (FIG. 3). These regions have the common structure (3′)AUACUUUUUUUNAUUGUCNNUAG(5′) (SEQ ID NO:34), in which N indicates any nucleotide (thus three variable positions are present) and the intergenic dinucleotide is underlined. These dinucleotide spacers are GA, except at the NS-M junction, where the dinucleotide is CA. The first 11 nucleotides of the common sequence are complementary to the sequence (5′) . . . UAUGAAAAAAA . . . (3′) (SEQ ID NO:35) that occurs at the mRNA-polyadenylate[poly(A)] junction in each mRNA including L. Reiterative copying of the U residues by the VSV polymerase presumably generates the poly(A) tail on each mRNA (McGeoch, 1979, Cell 17:3199; Rose, 1980, Cell 19:415; Schubert et al., 1980, J. Virol. 34:550). The sequence complementary to the 5′ end of the mRNA follows the intergenic dinucleotide. The L mRNA also terminates with the sequence UAUG-poly(A) encoded by the sequence (3′)AUACUUUUUUU (SEQ ID NO:36) and is presumably also polyadenylated by a polymerase “slippage” mechanism (Schubert et al., 1980, J. Virol. 34:550; Schubert and Lazarini, 1981, J. Virol. 38:256).

Thus, intergenic regions in vesiculovirus (−) DNA consist of three parts, triggering transcriptional termination and reinitiation present both 5′ and 3′ to each gene (presented as the 5′ to 3′ sequence of the positive sense strand of vesiculovirus (−) DNA): (a) TATGAAAAAAA (SEQ ID NO:37), followed by (b) the dinucleotide GT or CT, followed by (c) AACAG. Therefore, in a preferred aspect, foreign DNA encoding an Antigen can readily be expressed as a nonfusion protein from intergenic regions, simply by ensuring that this three-part intergenic region is reconstituted—i.e., that this intergenic region appears 5′ and 3′ to the foreign DNA and also 5′ and 3′ to the adjacent genes. For example, in a preferred embodiment, DNA consisting of (a) this three-part intergenic region, fused to (b) foreign DNA coding for a desired Antigen (preferably including the Antigen gene's native start and stop codons for initiation), is inserted into a portion of the vesiculovirus (−) DNA that is transcribed to form the 3′ noncoding region of any vesiculovirus mRNA. In a particularly preferred aspect, the foreign DNA is inserted in the noncoding region between G and L.

In an alternative embodiment, the foreign DNA can be inserted into the G gene, so as to encode a fusion protein with G, for resultant surface display of the Antigen on the vesiculovirus particle. Selection should be undertaken to ensure that the foreign DNA insertion does not disrupt G protein function.

In a preferred embodiment, an Antigen expressed by a recombinant vesiculovirus is all or a portion of an envelope glycoprotein of a virus other than a vesiculovirus. Such an Antigen can replace the endogenous vesiculovirus G protein in the vesiculovirus, or can be expressed as a fusion with the endogenous G protein, or can be expressed in addition to the endogenous G protein either as a fusion or nonfusion protein. In a specific embodiment, such an Antigen forms a part of the vesiculovirus envelope and thus is surface-displayed in the vesiculovirus particle. By way of example, gp160 or a fragment thereof of Human Immunodeficiency Virus can be the Antigen, which is cleaved to produce gp120 and gp41 (see Owens and Rose, 1993, J. Virol. 67(1):360-365). In a specific embodiment, the G gene of VSV in the VSV (−) DNA of plasmid pVSVFL(+) can be easily excised and replaced, by cleavage at the NheI and MluI sites flanking the G gene and insertion of the desired sequence. In another specific embodiment, the Antigen is a foreign envelope glycoprotein or portion thereof that is expressed as a fusion protein comprising the cytoplasmic domain (and, optionally, also the transmembrane region) of the native vesiculovirus G protein (see Owens and Rose, 1993, J. Virol. 67(1):360-365). Such a fusion protein can replace or be expressed in addition to the endogenous vesiculovirus G protein. As shown by way of example in Section 6 below, the entire native G coding sequence can be replaced by a coding sequence of a different G to produce recombinant replicable vesiculoviruses that express a non-native glycoprotein. While recombinant vesiculoviruses that express and display epitope(s) of envelope glycoproteins of other viruses can be used as live vaccines, such vesiculoviruses also are particularly useful as killed vaccines, as well as in the production of subunit vaccines containing the vesiculovirus-produced protein comprising such epitope(s).

In a specific embodiment, a recombinant vesiculovirus of the invention expresses in a host to which it is administered one or more Antigens. In one embodiment, a multiplicity of Antigens are expressed, each displaying different antigenicity or immunogenicity.

5.2. DNA Sequences Encoding Antigens

The invention provides recombinant vesiculoviruses capable of replication that have a foreign RNA sequence inserted into or replacing a site of the genome nonessential for replication, wherein the foreign RNA sequence (which is in the negative sense) directs the production of an Antigen capable of being expressed in a host infected by the recombinant virus. This recombinant genome is originally produced by insertion of foreign DNA encoding the Antigen into the vesiculovirus (−) DNA. Any DNA sequence which encodes an immunogenic (capable of provoking an immune response) Antigen, which produces prophylactic or therapeutic immunity against a disease or disorder, when expressed as a fusion or, preferably, nonfusion protein in a recombinant vesiculovirus of the invention, alone or in combination with other Antigens expressed by the same or a different vesiculovirus recombinant, can be isolated for use in the vaccine formulations of the present invention.

In a preferred embodiment, expression of an Antigen by a recombinant vesiculovirus induces an immune response against a pathogenic microorganism. For example, an Antigen may display the immunogenicity or antigenicity of an antigen found on bacteria, parasites, viruses, or fungi which are causative agents of diseases or disorders. In a preferred embodiment, Antigens displaying the antigenicity or immunogenicity of antigens of animal viruses of veterinary importance (for example, which cause diseases or disorders in non-human animals such as domestic or farm animals, e.g., cows, chickens, horses, dogs, cats, etc.) are used. In another embodiment, Antigens displaying the antigenicity or immunogenicity of an antigen of a human pathogen are used.

To determine immunogenicity or antigenicity by detecting binding to antibody, various immunoassays known in the art can be used, including but not limited to competitive and non-competitive assay systems using techniques such as radioimmunoassays, ELISA (enzyme linked immunosorbent assay), “sandwich” immunoassays, immunoradiometric assays, gel diffusion precipitin reactions, immunodiffusion assays, in situ immunoassays (using colloidal gold, enzyme or radioisotope labels, for example), western blots, immunoprecipitation reactions, agglutination assays (e.g., gel agglutination assays, hemagglutination assays), complement fixation assays, immunofluorescence assays, protein A assays, and immunoelectrophoresis assays, etc. In one embodiment, antibody binding is detected by detecting a label on the primary antibody. In another embodiment, the primary antibody is detected by detecting binding of a secondary antibody or reagent to the primary antibody. In a further embodiment, the secondary antibody is labelled. Many means are known in the art for detecting binding in an immunoassay and are envisioned for use. In one embodiment for detecting immunogenicity, T cell-mediated responses can be assayed by standard methods, e.g., in vitro cytoxicity assays or in vivo delayed-type hypersensitivity assays.

Parasites and bacteria expressing epitopes (antigenic determinants) that can be expressed by recombinant vesiculoviruses (wherein the foreign RNA directs the production of an antigen of the parasite or bacteria or a derivative thereof containing an epitope thereof) include but are not limited to those listed in Table II. TABLE II PARASITES AND BACTERIA EXPRESSING EPITOPES THAT CAN BE EXPRESSED BY RECOMBINANT VESICULOVIRUSES PARASITES:   Plasmodium spp.   Eimeria spp. BACTERIA:   Vibrio cholerae   Streptococcus pneumoniae   Neisseria mennigitidis   Neisseria gonorrhoeae   Corynebacteria diphtheriae   Clostridium tetani   Bordetella pertussis   Haemophilus spp. (e.g., influenzae)   Chlamydia spp.   Enterotoxigenic Escherichia coli

In another embodiment, the Antigen comprises an epitope of an antigen of a nematode, to protect against disorders caused by such worms.

In another specific embodiment, any DNA sequence which encodes a Plasmodium epitope, which when expressed by a recombinant vesiculovirus, is immunogenic in a vertebrate host, can be isolated for insertion into vesiculovirus (−) DNA according to the present invention. The species of Plasmaodium which can serve as DNA sources include but are not limited to the human malaria parasites P. falciparum, P. malariae, P. ovale, P. vivax, and the animal malaria parasites P. berghei, P. yoelii, P. knowlesi, and P. cynomolgi. In a particular embodiment, the epitope to be expressed is an epitope of the circumsporozoite (CS) protein of a species of Plasmodium (Miller et al., 1986, Science 234:1349).

In yet another embodiment, the Antigen comprises a peptide of the β subunit of Cholera toxin (Jacob et al., 1983, Proc. Natl. Acad. Sci. USA 80:7611).

Viruses expressing epitopes (antigenic determinants) that can be expressed by recombinant vesiculoviruses (wherein the foreign RNA directs the production of an antigen of the virus or a derivative thereof comprising an epitope thereof) include but are not limited to those listed in Table III, which lists such viruses by family for purposes of convenience and not limitation (see 1990, Fields Virology, 2d ed., Fields and Knipe (eds.), Raven Press, NY). TABLE III VIRUSES EXPRESSING EPITOPES THAT CAN BE EXPRESSED BY RECOMBINANT VESICULOVIRUSES I. Picornaviridae   Enteroviruses     Poliovirus     Coxsackievirus     Echovirus   Rhinoviruses   Hepatitis A Virus II. Caliciviridae   Norwalk group of viruses III. Togaviridae and Flaviviridae   Togaviruses (e.g., Dengue virus)   Alphaviruses   Flaviviruses (e.g., Hepatitis C virus)   Rubella virus IV. Coronaviridae   Coronaviruses V. Rhabdoviridae   Rabies virus VI. Filoviridae   Marburg viruses   Ebola viruses VII. Paramyxoviridae   Parainfluenza virus   Mumps virus   Measles virus   Respiratory syncytial virus VIII. Orthomyxoviridae   Orthomyxoviruses (e.g., Influenza virus) IX. Bunyaviridae   Bunyaviruses X. Arenaviridae   Arenaviruses XI. Reoviridae   Reoviruses   Rotaviruses   Orbiviruses XII. Retroviridae   Human T Cell Leukemia Virus type I   Human T Cell Leukemia Virus type II   Human Immunodeficiency Viruses (e.g.,     type I and type II)   Simian Immunodeficiency Virus   Lentiviruses XIII. Papoviridae   Polyomaviruses   Papillomaviruses   Adenoviruses XIV. Parvoviridae   Parvoviruses XV. Herpesviridae   Herpes Simplex Viruses   Epstein-Barr virus   Cytomegalovirus   Varicella-Zoster virus   Human Herpesvirus-6   Cercopithecine Herpes Virus 1 (B virus) XVI. Poxviridae   Poxviruses XVIII. Hepadnaviridae   Hepatitis B virus

In specific embodiments, the Antigen encoded by the foreign sequences that is expressed upon infection of a host by the recombinant vesiculovirus, displays the antigenicity or immunogenicity of an influenza virus hemagglutinin (Genbank accession no. JO2132; Air, 1981, Proc. Natl. Acad. Sci. USA 78:7639-7643.; Newton et al., 1983, Virology 128:495-501); human respiratory syncytial virus G glycoprotein (Genbank accession no. Z33429; Garcia et al., 1994, J. Virol.; Collins et al., 1984, Proc. Natl. Acad. Sci. USA 81:7683); core protein, matrix protein or other protein of Dengue virus (Genbank accession no. M19197; Hahn et al., 1988, Virology 162:167-180), measles virus hemagglutinin (Genbank accession no. M81899; Rota et al., 1992, Virology 188:135-142); and herpes simplex virus type 2 glycoprotein gB (Genbank accession no. M14923; Bzik et al., 1986, Virology 155:322-333).

In another embodiment, one or more epitopes of the fusion protein of respiratory synctyial virus (RSV) can be expressed as an Antigen.

Other Antigens that can be expressed by a recombinant vesiculovirus include but are not limited to those displaying the antigenicity or immunogenicity of the following antigens: Poliovirus I VP1 (Emini et al., 1983, Nature 304:699); envelope glycoproteins of HIV I (Putney et al., 1986, Science 234:1392-1395); Hepatitis B surface antigen (Itoh et al., 1986, Nature 308:19; Neurath et al., 1986, Vaccine 4:34); Diptheria toxin (Audibert et al., 1981, Nature 289:543); streptococcus 24M epitope (Beachey, 1985, Adv. Exp. Med. Biol. 185:193); and gonococcal pilin (Rothbard and Schoolnik, 1985, Adv. Exp. Med. Biol. 185:247).

In other embodiments, the Antigen expressed by the recombinant vesiculovirus displays the antigenicity or immunogenicity of pseudorabies virus g50 (gpD), pseudorabies virus II (gpB), pseudorabies virus gIII (gpC), pseudorabies virus glycoprotein H, pseudorabies virus glycoprotein E, transmissible gastroenteritis glycoprotein 195, transmissible gastroenteritis matrix protein, swine rotavirus glycoprotein 38, swine parvovirus capsid protein, Serpulina hydodysenteriae protective antigen, Bovine Viral Diarrhea glycoprotein 55, Newcastle Disease Virus hemagglutinin-neuraminidase, swine flu hemagglutinin, or swine flu neuraminidase.

In various embodiments, the Antigen expressed by the recombinant vesiculovirus displays the antigenicity or immunogenicity of an antigen derived from Serpulina hyodysenteriae, Foot and Mouth Disease Virus, Hog Colera Virus, swine influenza virus, African Swine Fever Virus, Mycoplasma hyopneumoniae, infectious bovine rhinotracheitis virus (e.g., infectious bovine rhinotracheitis virus glycoprotein E or glycoprotein G), or infectious laryngotracheitis virus (e.g., infectious laryngotracheitis virus glycoprotein G or glycoprotein I).

In another embodiment, the Antigen displays the antigenicity or immunogenicity of a glycoprotein of La Crosse Virus (Gonzales-Scarano et al., 1982, Virology 120:42), Neonatal Calf Diarrhea Virus (Matsuno and Inouye, 1983, Infection and Immunity 39:155), Venezuelan Equine Encephalomyelitis Virus (Mathews and Roehrig, 1982, J. Immunol. 129:2763), Punta Toro Virus (Dalrymple et al., 1981, in Replication of Negative Strand Viruses, Bishop and Compans (eds.), Elsevier, N.Y., p. 167), Murine Leukemia Virus (Steeves et al., 1974, J. Virol. 14:187), or Mouse Mammary Tumor Virus (Massey and Schochetman, 1981, Virology 115:20).

In another embodiment, the Antigen displays the antigenicity or immunogenicity of an antigen of a human pathogen, including but not limited to human herpesvirus, herpes simplex virus-1, herpes simplex virus-2, human cytomegalovirus, Epstein-Barr virus, Varicella-Zoster virus, human herpesvirus-6, human herpesvirus-7, human influenza virus, human immunodeficiency virus, rabies virus, measles virus, hepatitis B virus, hepatitis C virus, Plasmodium falciparum, and Bordetella pertussis.

In a specific embodiment of the invention, a recombinant vesiculovirus expresses hepatitis B virus core protein and/or hepatitis B virus surface antigen or a fragment or derivative thereof (see, e.g., U.K. Patent Publication No. GB 2034323A published Jun. 4, 1980; Ganem and Varmus, 1987, Ann. Rev. Biochem. 56:651-693; Tiollais et al., 1985, Nature 317:489-495). The HBV genome (subtype adw) is contained in plasmid pAM6 (Moriarty et al., 1981, Proc. Natl.

Acad. Sci. USA 78:2606-2610, available from the American Type Culture Collection (ATCC), Accession No. 45020), a pBR322-based vector that is replicable in E. coli.

In another embodiment, the Antigen expressed by the recombinant vesiculovirus displays the antigenicity or immunogenicity of an antigen of equine influenza virus or equine herpesvirus. Examples of such antigens are equine influenza virus type A/Alaska 91 neuraminidase, equine influenza virus type A/Miami 63 neuraminidase, equine influenza virus type A/Kentucky 81 neuraminidase equine herpesvirus type 1 glycoprotein B, and equine herpesvirus type 1 glycoprotein D.

In another embodiment, the Antigen displays the antigenicity or immunogenicity of an antigen of bovine respiratory syncytial virus or bovine parainfluenza virus. For example, such antigens include but are not limited to bovine respiratory syncytial virus attachment protein (BRSV G), bovine respiratory syncytial virus fusion protein (BRSV F), bovine respiratory syncytial virus nucleocapsid protein (BRSV N), bovine parainfluenza virus type 3 fusion protein, and the bovine parainfluenza virus type 3 hemagglutinin neuraminidase.

In another embodiment, the Antigen displays the antigenicity or immunogenicity of bovine viral diarrhea virus glycoprotein 48 or glycoprotein 53.

In another embodiment, the Antigen displays the antigenicity or immunogenicity of an antigen of infectious bursal disease virus. Examples of such antigens are infectious bursal disease virus polyprotein and VP2.

Potentially useful antigens or derivatives thereof for use as Antigens expressed by recombinant vesiculoviruses can be identified by various criteria, such as the antigen's involvement in neutralization of a pathogen's infectivity (Norrby, 1985, Summary, in Vaccines85, Lerner et al. (eds.), Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y., pp. 388-389), type or group specificity, recognition by patients' antisera or immune cells, and/or the demonstration of protective effects of antisera or immune cells specific for the antigen. In addition, the antigen's encoded epitope should preferably display a small or no degree of antigenic variation in time or amongst different isolates of the same pathogen.

In a preferred embodiment, the foreign DNA inserted into the vesiculovirus (−) DNA encodes an immunopotent dominant epitope of a pathogen. Foreign DNA encoding epitopes which are reactive with antibody although incapable of eliciting immune responses, still have potential uses in immunoassays (see Section 5.8, infra).

In another embodiment, foreign RNA of the recombinant vesiculovirus directs the production of an Antigen comprising an epitope, which when the recombinant vesiculovirus is introduced into a desired host, induces an immune response that protects against a condition or disorder caused by an entity containing the epitope. For example, the Antigen can be a tumor specific antigen or tumor-associated antigen, for induction of a protective immune response against a tumor (e.g., a malignant tumor). Such tumor-specific or tumor-associated antigens include but are not limited to KS ¼ pan-carcinoma antigen (Perez and Walker, 1990, J. Immunol. 142:3662-3667; Bumal, 1988, Hybridoma 7(4):407-415); ovarian carcinoma antigen (CA125) (Yu et al., 1991, Cancer Res. 51(2):468-475); prostatic acid phosphate (Tailor et al., 1990, Nucl. Acids Res. 18(16):4928); prostate specific antigen (Henttu and Vihko, 1989, Biochem. Biophys. Res. Comm. 160(2):903-910; Israeli et al., 1993, Cancer Res. 53:227-230; melanoma-associated antigen p97 (Estin et al., 1989, J. Natl. Cancer Instit. 81(6):445-446); melanoma antigen gp75 (Vijayasardahl et al., 1990, J. Exp. Med. 171(4):1375-1380); high molecular weight melanoma antigen (Natali et al., 1987, Cancer 59:55-63); and prostate specific membrane antigen.

In another embodiment of the invention, the Antigen expressed by the recombinant vesiculovirus comprises large regions of proteins which contain several B cell epitopes (i.e., epitopes capable of enticing a humoral immune response) and T cell epitopes (i.e., epitopes capable of inducing a cell-mediated immune response).

Peptides or proteins which are known to contain antigenic determinants can be used as the Antigen. If specific desired antigens are unknown, identification and characterization of immunoreactive sequences can be carried out. One way in which to accomplish this is through the use of monoclonal antibodies generated to the surface or other molecules of a pathogen or tumor, as the case may be. The peptide sequences capable of being recognized by the antibodies are defined epitopes. Alternatively, small synthetic peptides conjugated to carrier molecules can be tested for generation of monoclonal antibodies that bind to the sites corresponding to the peptide, on the intact molecule (see, e.g., Wilson et al., 1984, Cell 37:767).

In a specific embodiment, appropriate Antigens, including fragments or derivatives of known antigens, can be identified by virtue of their hydrophilicity, by carrying out a hydrophilicity analysis (Hopp and Woods, 1981, Proc. Natl. Acad. Sci. USA 78:3824) to generate a hydrophilicity profile. A hydrophilicity profile can be used to identify the hydrophobic and hydrophilic regions of a protein and the corresponding regions of the gene sequence which encode such proteins. Hydrophilic regions are predicted to be immunogenic/antigenic. Other methods known in the art which may be employed for the identification and characterization of antigenic determinants are also within the scope of the invention.

The foreign DNA encoding the Antigen, that is inserted into a non-essential site of the vesiculovirus (−) DNA, optionally can further comprise a foreign DNA sequence encoding a cytokine capable of being expressed and stimulating an immune response in a host infected by the recombinant vesiculovirus. For example, such cytokines include but are not limited to interleukin-2, interleukin-6, interleukin-12, interferons, granulocyte-macrophage colony stimulating factors, and interleukin receptors.

The foreign DNA optionally can further comprise a sequence encoding and capable of expressing a detectable marker (e.g., β galactosidase).

5.3. Construction of Vesiculovirus (−) DNA Containing Foreign DNA

For initial production of a recombinant vesiculovirus, the foreign DNA comprising a sequence encoding the desired antigen is inserted into and/or replaces a region of the vesiculovirus (−) DNA nonessential for replication. Many strategies known in the art can be used in the construction of the vesiculovirus (−) DNA containing the foreign DNA. For example, the relevant sequences of the foreign DNA and of the vesiculovirus (−) DNA can, by techniques known in the art, be cleaved at appropriate sites with restriction endonuclease(s), isolated, and ligated in vitro. If cohesive termini are generated by restriction endonuclease digestion, no further modification of DNA before ligation may be needed. If, however, cohesive termini of the DNA are not available for generation by restriction endonuclease digestion, or different sites other than those available are preferred, any of numerous techniques known in the art may be used to accomplish ligation of the heterologous DNA at the desired sites. In a preferred embodiment, a desired restriction enzyme site is readily introduced into the desired DNA by amplification of the DNA by use of PCR with primers containing the restriction enzyme site. By way of another example, cleavage with a restriction enzyme can be followed by modification to create blunt ends by digesting back or filling in single-stranded DNA termini before ligation. Alternatively, the cleaved ends of the vesiculovirus (−) DNA or foreign DNA can be “chewed back” using a nuclease such as nuclease Bal 31, exonuclease III, lambda exonuclease, mung bean nuclease, or T4 DNA polymerase exonuclease activity, to name but a few, in order to remove portions of the sequence.

To facilitate insertion of the foreign DNA, an oligonucleotide sequence (a linker) which encodes one or more restriction sites can be inserted in a region of the vesiculovirus (−) DNA (see, e.g., the polylinker in pVSVSS1, FIG. 2) by ligation to DNA termini. A linker may also be used to generate suitable restriction sites in the foreign DNA sequence.

Additionally, vesiculovirus (−) DNA or foreign DNA sequences can be mutated in vitro or in vivo in order to form new restriction endonuclease sites or destroy preexisting ones, to facilitate in vitro ligation procedures. Any technique for mutagenesis known in the art can be used, including but not limited to, in vitro site-directed mutagenesis (Hutchinson et al., 1978, J. Biol. Chem. 253:6551), chemical mutagenesis, etc.

Sequences of the vesiculovirus (−) DNA that have been undesirably modified by such in vitro manipulations can be “restored,” if desired, by introduction of appropriate sequences at the desired sites.

The particular strategy for inserting the foreign DNA will depend on the specific vesiculovirus (−) DNA site to be replaced or inserted into, as well as the foreign DNA to be inserted.

The sequences encoding the immunogenic peptides or proteins are preferably present in single copies, but can also be present in multiple copies within the virus genome.

Formation of the desired vesiculovirus (−) DNA containing the foreign DNA can be confirmed by standard methods such as DNA sequence analysis, hybridization analysis, and/or restriction mapping, using methods well known in the art.

Foreign DNA encoding a desired antigen can be obtained from any of numerous sources such as cloned DNA, genomic DNA, or cDNA made from RNA of the desired pathogen or tumor, as the case may be, or chemically synthesized DNA, and manipulated by recombinant DNA methodology well known in the art (see Sambrook et al., 1991, Molecular Cloning, A Laboratory Manual, 2d ed., Cold Spring Harbor Laboratory Press, New York). In a preferred embodiment, polymerase chain reaction (PCR) is used to amplify the desired fragment of foreign DNA from among a crude preparation of DNA or a small sample of the DNA, by standard methods. Appropriate primers for use in PCR can be readily deduced based on published sequences.

In order to generate appropriate DNA fragments, the DNA (e.g., from the pathogen or tumor of interest) may be cleaved at specific sites using various restriction enzymes. Alternatively, one may use DNaseI in the presence of manganese, or mung bean nuclease (McCutchan et al., 1984, Science 225:626), to fragment the DNA, or the DNA can be physically sheared, as for example, by sonication. The linear DNA fragments can then be separated according to size by standard techniques, including, but not limited to, agarose and polyacrylamide gel electrophoresis and column chromatography.

PCR amplification of DNA fragments containing the desired epitope(s) is most preferably carried out, in which the PCR primers contain and thus introduce into the amplified DNA a desired restriction enzyme recognition site. Alternatively, any restriction enzyme or combination of restriction enzymes may be used to generate DNA fragment(s) containing the desired epitope(s), provided the enzymes do not destroy the immunopotency of the encoded product. Consequently, many restriction enzyme combinations may be used to generate DNA fragments which, when inserted into the vesiculovirus (−) DNA, are capable of producing recombinant vesiculoviruses that direct the production of the peptide containing the epitope(s).

Once the DNA fragments are generated, identification of the specific fragment containing the desired sequence may be accomplished in a number of ways. For example, if a small amount of the desired DNA sequence or a homologous sequence is previously available, it can be used as a labeled probe (e.g., nick translated) to detect the DNA fragment containing the desired sequence, by nucleic acid hybridization. Alternatively, if the sequence of the derived gene or gene fragment is known, isolated fragments or portions thereof can be sequenced by methods known in the art, and identified by a comparison of the derived sequence to that of the known DNA or protein sequence. Alternatively, the desired fragment can be identified by techniques including but not limited to mRNA selection, making cDNA to the identified mRNA, chemically synthesizing the gene sequence (provided the sequence is known), or selection on the basis of expression of the encoded protein (e.g., by antibody binding) after “shotgun cloning” of various DNA fragments into an expression system.

The sequences encoding peptides to be expressed in recombinant vesiculoviruses according to the present invention, whether produced by recombinant DNA methods, chemical synthesis, or purification techniques, include but are not limited to sequences encoding all or part (fragments) of the amino acid sequences of pathogen-specific and tumor-specific antigens, as well as other derivatives and analogs thereof displaying the antigenicity or immunogenicity thereof. Derivatives or analogs of antigens can be tested for the desired activity by procedures known in the art, including but not limited to standard immunoassays.

In particular, antigen derivatives can be made by altering the encoding antigen nucleotide sequences by substitutions, additions or deletions that do not destroy the antigenicity or immunogenicity of the antigen. For example, due to the degeneracy of nucleotide coding sequences, other DNA sequences which encode substantially the same amino acid sequence as a native antigen gene or portion thereof may be used in the practice of the present invention. Other examples may include but are not limited to nucleotide sequences comprising all or portions of genes or cDNAs which are altered by the substitution of different codons that encode a functionally equivalent amino acid residue within the sequence, thus producing a silent change. For example, one or more amino acid residues within the sequence can be substituted by another amino acid of a similar polarity which acts as a functional equivalent, resulting in a silent alteration. Substitutes for an amino acid within the sequence may be selected from other members of the class to which the amino acid belongs. For example, the nonpolar (hydrophobic) amino acids include alanine, leucine, isoleucine, valine, proline, phenylalanine, tryptophan, and methionine. The polar neutral amino acids include glycine, serine, threonine, cysteine, tyrosine, asparagine, and glutamine. The positively charged (basic) amino acids include arginine, lysine, and histidine. The negatively charged (acidic) amino acids include aspartic and glutamic acid.

The antigen derivatives and analogs can be produced by various methods known in the art. For example, a cloned gene sequence can be modified by any of numerous strategies known in the art (Sambrook et al., 1989, Molecular Cloning, A Laboratory Manual, 2d ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.). The sequence can be cleaved at appropriate sites with restriction endonuclease(s), followed by further enzymatic modification if desired, isolated, and ligated in vitro. In the production of the gene encoding a derivative or analog of an antigen, care should be taken to ensure that the modified gene remains within the same translational reading frame as the antigen, uninterrupted by translational stop signals, in the gene region where the desired epitope(s) are encoded.

Additionally, the antigen-encoding nucleic acid sequence can be mutated in vitro or in vivo, to create and/or destroy translation, initiation, and/or termination sequences, or to create variations in coding regions and/or form new restriction endonuclease sites or destroy preexisting ones, to facilitate further in vitro modification. Any technique for mutagenesis known in the art can be used, including but not limited to, in vitro site-directed mutagenesis (Hutchinson, C., et al., 1978, J. Biol. Chem 253:6551), use of TAB® linkers (Pharmacia), etc.

In another specific embodiment, the encoded antigen derivative is a chimeric, or fusion, protein comprising a first protein or fragment thereof fused to a second, different amino acid sequence. Such a chimeric protein is encoded by a chimeric nucleic acid in which the two coding sequences are joined inframe. Such a chimeric product can be made by ligating the appropriate nucleic acid sequences encoding the desired amino acid sequences to each other by methods known in the art, in the proper coding frame. In a specific embodiment, a fusion protein is produced in which the first protein sequence contains an epitope of an antigen, and the second protein sequence contains an epitope of a different antigen.

Derivatives and fragments of known antigens can be readily tested by standard immunoassay techniques to ascertain if they display the desired immunogenicity or antigenicity, rendering a DNA sequence encoding such a fragment or derivative suitable for insertion into the vesiculovirus (−) DNA.

A DNA sequence encoding an epitope that is a hapten, i.e., a molecule that is antigenic in that it can react selectively with cognate antibodies, but not immunogenic in that it cannot elicit an immune response when administered without adjuvants or carrier proteins, can also be isolated for use, since it is envisioned that, in particular embodiments, presentation by the vesiculoviruses of the invention can confer immunogenicity to the hapten expressed by the virus.

Once identified and isolated, the foreign DNA containing the sequence(s) of interest is then inserted into the vesiculovirus (−) DNA, for production of a recombinant vesiculovirus.

5.4. Production of Recombinant Vesiculoviruses

The recombinant vesiculoviruses of the invention are produced by providing in an appropriate host cell: vesiculovirus (−) DNA, in which regions nonessential for replication have been inserted into or replaced by foreign DNA comprising a sequence encoding an Antigen, and recombinant sources of vesiculovirus N protein, P protein, and L protein. The production is preferably in vitro, in cell culture.

The host cell used for recombinant vesiculovirus production can be any cell in which vesiculoviruses grow, e.g., mammalian cells and some insect (e.g., Drosophila) cells. Primary cells, or more preferably, cell lines can be used. A vast number of cell lines commonly known in the art are available for use. By way of example, such cell lines include but are not limited to BHK (baby hamster kidney) cells, CHO (Chinese hamster ovary) cells, HeLA (human) cells, mouse L cells, Vero (monkey) cells, ESK-4, PK-15, EMSK cells, MDCK (Madin-Darby canine kidney) cells, MDBK (Madin-Darby bovine kidney) cells, 293 (human) cells, and Hep-2 cells.

The sources of N, P, and L proteins can be the same or different recombinant nucleic acid(s), encoding and capable of expressing the N, P and L proteins in the host cell in which it is desired to produce recombinant vesiculovirus.

The nucleic acids encoding the N, P and L proteins are obtained by any means available in the art. The N, P and L nucleic acid sequences have been disclosed and can be used. For example, see Genbank accession no. J02428; Rose and Schubert, 1987, in The Viruses: The Rhabdoviruses, Plenum Press, NY, pp. 129-166. The sequences encoding the N, P and L genes can also be obtained from plasmid pVSVFL(+), deposited with the ATCC and assigned accession no. ______, e.g., by PCR amplification of the desired gene (PCR; U.S. Pat. Nos. 4,683,202, 4,683,195 and 4,889,818; Gyllenstein et al., 1988, Proc. Natl. Acad. Sci. USA 85:7652-7656; Ochman et al., 1988, Genetics 120:621-623; Loh et al., 1989, Science 243:217-220). If a nucleic acid clone of any of the N, P or L genes is not already available, the clone can be obtained by use of standard recombinant DNA methodology. For example, the DNA may be obtained by standard procedures known in the art by purification of RNA from vesiculoviruses followed by reverse transcription and polymerase chain reaction (Mullis and Faloona, 1987, Methods in Enzymology 155:335-350). Alternatives to isolating an N, P or L gene include, but are not limited to, chemically synthesizing the gene sequence itself. Other methods are possible and within the scope of the invention.

If desired, the identified and isolated gene can then optimally be inserted into an appropriate cloning vector prior to transfer to an expression vector.

Nucleic acids that encode derivatives (including fragments) and analogs of native N, P and L genes, as well as derivatives and analogs of the vesiculovirus (−) DNA can also be used in the present invention, as long as such derivatives and analogs retain function, as exemplified by the ability when used according to the invention to produce a replicable vesiculovirus containing a genomic RNA containing foreign RNA. In particular, derivatives can be made by altering sequences by substitutions, additions, or deletions that provide for functionally active molecules. Furthermore, due to the inherent degeneracy of nucleotide coding sequences, other DNA sequences which encode substantially the same or a functionally equivalent amino acid sequence may be used in the practice of the methods of the invention. Amino acid substitutions may be made on the basis of similarity in polarity, charge, solubility, hydrophobicity, hydrophilicity and/or the amphipathic nature of the residues involved.

The desired N/P/L-encoding nucleic acid is then preferably inserted into an appropriate expression vector, i.e., a vector which contains the necessary elements for the transcription and translation of the inserted protein-coding sequence in the host in which it is desired to produce recombinant vesiculovirus, to create a vector that functions to direct the synthesis of the N/P/L protein that will subsequently assemble with the vesiculovirus genomic RNA containing the foreign sequence (produced in the host cell from antigenomic vesiculovirus (+) RNA produced by transcription of the vesiculovirus (−) DNA). A variety of vector systems may be utilized to express the N, P and L-coding sequences, as well as to transcribe the vesiculovirus (−) DNA containing the foreign DNA, as long as the vector is functional in the host and compatible with any other vector present. Such vectors include but are not limited to bacteriophages, plasmids, or cosmids. In a preferred aspect, a plasmid expression vector is used. The expression elements of vectors vary in their strengths and specificities. Any one of a number of suitable transcription and translation elements may be used, as long as they are functional in the host.

Standard recombinant DNA methods may be used to construct expression vectors containing DNA encoding the N, P, and L proteins, and the vesiculovirus (−) DNA containing the foreign DNA, comprising appropriate transcriptional/translational control signals (see, e.g., Sambrook et al., 1989, supra, and methods described hereinabove). (Translational control signals are not needed for transcription of the vesiculovirus (−) DNA, and thus may be omitted from a vector containing the vesiculovirus (−) DNA, although such signals may be present in the vector and operably linked to other sequences encoding a protein which it is desired to express). Expression may be controlled by any promoter/enhancer element known in the art. Promoters which may be used to control expression can be constitutive or inducible. In a specific embodiment, the promoter is an RNA polymerase promoter.

Transcription termination signals (downstream of the gene), and selectable markers are preferably also included in a plasmid expression vector. In addition to promoter sequences, expression vectors for the N. P, and L proteins preferably contain specific initiation signals for efficient translation of inserted N/P/L sequences, e.g., a ribosome binding site.

Specific initiation signals are required for efficient translation of inserted protein coding sequences. These signals include the ATG initiation codon and adjacent sequences. In cases where the entire N, P, or L gene including its own initiation codon and adjacent sequences are inserted into the appropriate vectors, no additional translational control signals may be needed. However, in cases where only a portion of the gene sequence is inserted, exogenous translational control signals, including the ATG initiation codon, must be provided. The initiation codon must furthermore be in phase with the reading frame of the protein coding sequences to ensure translation of the entire insert. These exogenous translational control signals and initiation codons can be of a variety of origins, both natural and synthetic.

In a specific embodiment, a recombinant expression vector provided by the invention, encoding an N, P, and/or L protein or functional derivative thereof, comprises the following operatively linked components: a promoter which controls the expression of the N, P, or L protein or functional derivative thereof, a translation initiation signal, a DNA sequence encoding the N, P or L protein or functional derivative thereof, and a transcription termination signal. In a preferred aspect, the above components are present in 5′ to 3′ order as listed above.

In another specific embodiment, the gene encoding the N, P, or L protein is inserted downstream of the T7 RNA polymerase promoter from phage T7 gene 10, situated with an A in the −3 position. A T7 RNA polymerase terminator and a replicon are also included in the expression vector. In this embodiment, T7 RNA polymerase is provided to transcribe the N/P/L sequence. The T7 RNA polymerase can be produced from a chromosomally integrated sequence or episomally, and is most preferably provided by intracellular expression from a recombinant vaccinia virus encoding the T7 RNA polymerase (see infra). Preferably, the N, P, and L proteins are each encoded by a DNA sequence operably linked to a promoter in an expression plasmid, containing the necessary regulatory signals for transcription and translation of the N, P, and L proteins. Such an expression plasmid preferably includes a promoter, the coding sequence, and a transcription termination/polyadenylation signal, and optionally, a selectable marker (e.g., β-galactosidase). The N, P and L proteins can be encoded by the same or different plasmids, or a combination thereof, and preferably are in different plasmids. Less preferably, one or more of the N, P, and L proteins can be expressed intrachromosomally.

The cloned sequences comprising the vesiculovirus (−) DNA containing the foreign DNA, and the cloned sequences comprising sequences encoding the N, P, and L proteins can be introduced into the desired host cell by any method known in the art, e.g., transfection, electroporation, infection (when the sequences are contained in, e.g., a viral vector), microinjection, etc.

In a preferred embodiment, DNA comprising vesiculovirus (−) DNA containing foreign DNA encoding an Antigen, operably linked to an RNA polymerase promoter (preferably a bacteriophage RNA polymerase promoter); DNA encoding N, operably linked to the same RNA polymerase promoter; DNA encoding P, operably linked to the same polymerase promoter; and DNA encoding L, operably linked to the same polymerase promoter; are all introduced (preferably by transfection) into the same host cell, in which host cell the RNA polymerase has been cytoplasmically provided. The RNA polymerase is cytoplasmically provided preferably by expression from a recombinant virus that replicates in the cytoplasm and expresses the RNA polymerase, most preferably a vaccinia virus (see the section hereinbelow), that has been introduced (e.g., by infection) into the same host cell. Cytoplasmic provision of RNA polymerase is preferred, since this will result in cytoplasmic transcription and processing, of the VSV (−) DNA comprising the foreign DNA and of the N, P and L proteins, avoiding splicing machinery in the cell nucleus, and thus maximizing proper processing and production of N, P and L proteins, and resulting assembly of the recombinant vesiculovirus. For example, vaccinia virus also cytoplasmically provides enzymes for processing (capping and polyadenylation) of mRNA, facilitating proper translation. In a most preferred aspect, T7 RNA polymerase promoters are employed, and a cytoplasmic source of T7 RNA polymerase is provided by also introducing into the host cell a recombinant vaccinia virus encoding T7 RNA polymerase into the host cell. Such vaccinia viruses can be obtained by well known methods (see section 5.5, infra). In a preferred aspect, a recombinant vaccinia virus such as vTF7-3 (Fuerst et al., 1986, Proc. Natl. Acad. Sci. U.S.A. 83:8122-8126) can be used. In a most preferred aspect, the DNA comprising vesiculovirus (−) DNA containing foreign DNA is plasmid pVSVSS1 in which foreign DNA has been inserted into the polylinker region.

Alternatively, but less preferably, the RNA polymerase (e.g., T7 RNA polymerase) can be provided by use of a host cell that expresses T7 RNA polymerase from a chromosomally integrated sequence (e.g., originally inserted into the chromosome by homologous recombination), preferably constitutively, or that expresses T7 RNA polymerase episomally, from a plasmid.

In another, less preferred, embodiment, the VSV (−) DNA encoding an Antigen, operably linked to a promoter, can be transfected into a host cell that stably recombinantly expresses the N, P, and L proteins from chromosomally integrated sequences.

The cells are cultured and recombinant vesiculovirus is recovered, by standard methods. For example, and not by limitation, after approximately 24 hours, cells and medium are collected, freeze-thawed, and the lysates clarified to yield virus preparations. Alternatively, the cells and medium are collected and simply cleared of cells and debris by low-speed centrifugation.

Confirmation that the appropriate foreign sequence is present in the genome of the recombinant vesiculovirus and directs the production of the desired protein(s) in an infected cell, is then preferably carried out. Standard procedures known in the art can be used for this purpose. For example, genomic RNA is obtained from the vesiculovirus by SDS phenol extraction from virus preparations, and can be subjected to reverse transcription (and PCR, if desired), followed by sequencing, Southern hybridization using a probe specific to the foreign DNA, or restriction enzyme mapping, etc. The virus can be used to infect host cells, which can then be assayed for expression of the desired protein by standard immunoassay techniques using an antibody to the protein, or by assays based on functional activity of the protein. Other techniques are known in the art and can be used.

The invention also provides kits for production of recombinant vesiculoviruses. In one embodiment, the kit comprises in one or more (and most preferably, in separate) containers: (a) a first recombinant DNA that can be transcribed in a suitable host cell to produce a vesiculovirus antigenomic (+) RNA in which a portion of the RNA nonessential for replication of the vesiculovirus has been inserted into or replaced by a foreign RNA sequence; (b) a second recombinant DNA comprising a sequence encoding a vesiculovirus N protein; (c) a third recombinant DNA comprising a sequence encoding a vesiculovirus L protein; and (d) a fourth recombinant DNA comprising a sequence encoding a vesiculovirus P protein. The second, third and fourth recombinant DNAs can be part of the same or different DNA molecules. In a preferred embodiment, the sequences encoding the N, L, and P proteins are each operably linked to a promoter that controls expression of the N. L, and P proteins, respectively, in the suitable host cell. In various embodiments, the kit can contain the various nucleic acids, e.g., plasmid expression vectors, described hereinabove for use in production of recombinant vesiculoviruses.

In another embodiment, a kit of the invention comprises (a) a first recombinant DNA that can be transcribed in a suitable host cell to produce a vesiculovirus antigenomic DNA in which a portion of the RNA nonessential for replication of the vesiculovirus has been inserted into or replaced by a foreign RNA sequence; and (b) a host cell that recombinantly expresses vesiculovirus N, P and L proteins.

In a preferred embodiment, a kit of the invention comprises in separate containers:

-   -   (a) a first plasmid comprising the following operatively linked         components: (i) a bacteriophage RNA polymerase promoter, (ii) a         DNA comprising a sequence capable of being transcribed in a         suitable host cell to produce an RNA molecule comprising a         vesiculovirus antigenomic RNA in which a portion of the RNA         nonessential for replication of the vesiculovirus has been         inserted into or replaced by a foreign RNA sequence, and in         which the 3′ end of the antigenomic RNA is immediately adjacent         to a ribozyme sequence that cleaves at the 3′ end of the         antigenomic RNA, and (iii) a transcriptional termination signal         for the bacteriophage RNA polymerase; and     -   (b) a second plasmid comprising the following operatively linked         components: (i) the bacteriophage RNA polymerase promoter, (ii)         a DNA comprising a sequence encoding the vesiculovirus N         protein, and (ii) a transcriptional termination signal for the         bacteriophage RNA polymerase; and     -   (c) a third plasmid comprising the following operatively linked         components: (i) the bacteriophage RNA polymerase promoter, (ii)         a DNA comprising a sequence encoding the vesiculovirus P         protein, and (ii) a transcriptional termination signal for the         bacteriophage RNA polymerase; and     -   (d) a fourth plasmid comprising the following operatively linked         components: (i) the bacteriophage RNA polymerase promoter, (ii)         a DNA comprising a sequence encoding the vesiculovirus L         protein, and (ii) a transcriptional termination signal for the         bacteriophage RNA polymerase.

In another embodiment, a kit of the invention further comprises in a separate container a recombinant vaccinia virus encoding and capable of expressing the bacteriophage RNA polymerase.

In a preferred embodiment, the components in the containers are in purified form.

5.4.1. Recombinant Vaccinia Viruses Encoding and Capable of Expressing Foreign RNA Polymerases

In a preferred aspect of-the invention, transcription of the vesiculovirus (−) DNA containing the foreign DNA encoding an Antigen, and/or transcription of the DNA encoding the N, P, and L proteins in the host cell, is controlled by an RNA polymerase promoter (preferably one in which the RNA polymerase is not endogenous to the host cell), and the RNA polymerase (that initiates transcription from the promoter) is recombinantly provided in the host cell by expression from a recombinant vaccinia virus. DNA sequences encoding RNA polymerases are well known and available in the art and can be used. For example, phage DNA can be obtained and PCR used to amplify the desired polymerase gene.

Insertion of the desired recombinant DNA sequence encoding and capable of expressing the RNA polymerase into a vaccinia virus for expression by the vaccinia virus is preferably accomplished by first inserting the DNA sequence into a plasmid vector which is capable of subsequent transfer to a vaccinia virus genome by homologous recombination. Thus, in a preferred aspect of the invention for constructing the recombinant vaccinia viruses, the desired DNA sequence encoding the polymerase is inserted, using recombinant DNA methodology (see Sambrook et al., 1989, Molecular Cloning, A Laboratory Manual, 2d ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.) into an insertion (preferably, plasmid) vector flanked by (preferably) nonessential vaccinia DNA sequences, thus providing for subsequent transfer of its chimeric gene(s) into vaccinia virus by homologous recombination. The sequences are placed in the vector such that they can be expressed under the control of a promoter functional in vaccinia virus.

Expression of foreign DNA in recombinant vaccinia viruses requires the positioning of promoters functional in vaccinia so as to direct the expression of the protein-coding polymerase DNA sequences. Plasmid insertion vectors have been constructed to insert chimeric genes into vaccinia virus for expression therein. Examples of such vectors are described by Mackett (Mackett et al., 1984. J. Virol. 49:857-864). The DNA encoding the polymerase is inserted into a suitable restriction endonuclease cloning site. In addition to plasmid insertion vectors, insertion vectors based on single-stranded M13 bacteriophage DNA (Wilson et al., 1986, Gene 49:207-213) can be used.

The inserted polymerase DNA should preferably not contain introns, and insertion should preferably be so as to place the coding sequences in close proximity to the promoter, with no other start codons in between the initiator ATG and the 5′ end of the transcript.

The plasmid insertion vector should contain transcriptional and translational regulatory elements that are active in vaccinia virus. The plasmid should be configured so that the polymerase sequences are under the control of a promoter active in vaccinia virus. Promoters which can be used in the insertion vectors include but are not limited to the vaccinia virus thymidine kinase (TK) promoter, the 7.5K promoter (Cochran et al., 1985, J. Virol. 54:30-37), the 11K promoter (European Patent Publication 0198328), the F promoter (Paoletti et al., 1984, Proc. Natl. Acad. Sci. USA 81:193-197), and various early and late vaccinia promoters (see Moss, 1990, Virology, 2d ed., ch. 74, Fields et al., eds., Raven Press, Ltd., New York, pp. 2079-2111).

In a specific embodiment, the plasmid insertion vector contains (for eventual transfer into vaccinia virus) a T7 RNA polymerase coding sequence under the control of a promoter active in vaccinia virus. In another specific embodiment, a plasmid insertion vector contains a co-expression system consisting of divergently oriented promoters, one directing transcription of the polymerase sequences, the other directing transcription of a reporter gene or selectable marker, to facilitate detection or selection of the eventual recombinant vaccinia virus (see, e.g., Fuerst et al., 1987, Mol. Cell. Biol. 5:1918-1924).

As described supra, the plasmid insertion vector contains at least-one set of polymerase coding sequences operatively linked to a promoter, flanked by sequences preferably nonessential for vaccinia viral replication. Such nonessential sequences include but are not limited to the TK gene (Mackett et al., 1984, J. Virol. 49:857-864), the vaccinia HindIII-F DNA fragment (Paoletti et al., 1984, Proc. Natl. Acad. Sci. USA 81:193-197), the vaccinia growth factor gene situated within both terminal repeats (Buller et al., 1988, J. Virol. 62:866-874), the N2 and M1 genes (Tamin et al., 1988, Virology 165:141-150), the M1 subunit of the ribonucleotide reductase gene in the vaccinia HindIII-I DNA fragment (Child et al., 1990, Virology 174:625-629), the vaccinia hemagglutinin (Shida et al., 1988, J. Virol. 62:4474-4480), vaccinia 14 kD fusion protein gene (Rodriguez et al., 1989, Proc. Natl. Acad. Sci. USA 86:1287-1291), etc. (see also Buller and Palumbo, 1991, Microbiol. Rev. 55(1):80-122). TK sequences are preferred for use; use of such sequences results in the generation of TK⁻ recombinant viruses.

Recombinant vaccinia viruses are preferably produced by transfection of the recombinant insertion vectors containing the polymerase sequences into cells previously infected with vaccinia virus. Alternatively, transfection can take place prior to infection with vaccinia virus. Homologous recombination takes place within the infected cells and results in the insertion of the foreign gene into the viral genome, in the region corresponding to the insertion vector flanking regions. The infected cells can be screened using a variety of procedures such as immunological techniques, DNA plaque hybridization, or genetic selection for recombinant viruses which subsequently can be isolated. These vaccinia recombinants preferably retain their essential functions and infectivity and can be constructed to accommodate up to approximately 35 kilobases of foreign DNA.

Transfections may be performed by procedures known in the art, for example, a calcium chloride-mediated procedure (Mackett et al., 1985, The construction and characterization of vaccinia virus recombinants expressing foreign genes, in DNA Cloning, Vol. II, Rickwood and Hames (eds.), IRL Press, Oxford-Washington, D.C.) or a liposome-mediated procedure (Rose et al., 1991, Biotechniques 10:520-525).

Where, as is preferred, flanking TK sequences are used to promote homologous recombination, the resulting recombinant viruses thus have a disrupted TK region, permitting them to grow on a TK host cell line such as Rat2 (ATCC Accession No. CRL 1764) in the presence of 5-bromo-2′-deoxyuridine (BUDR), under which conditions non-recombinant (TK⁺) viruses will not grow.

In another embodiment, recombinant vaccinia viruses of the invention can be made by in vitro cloning, and then packaging with a poxvirus sensitive to a selection condition, rather than by homologous recombination (see International Publication No. WO 94/12617 dated Jun. 9, 1994). For example, the HBV DNA sequences can be inserted into vaccinia genomic DNA using standard recombinant DNA techniques in vitro; this recombinant DNA can then be packaged in the presence of a “helper” poxvirus such as a temperature sensitive vaccinia virus mutant or a fowlpox virus which can be selected against under the appropriate conditions.

Various vaccinia virus strains known in the art can be used to generate the recombinant viruses of the invention. A preferred vaccinia virus is the New York City Department of Health Laboratories strain, prepared by Wyeth (available from the American Type Culture Collection (ATCC), Accession No. VR-325). Other vaccinia strains include but are not limited to the Elstree and Moscow strains, the strain of Rivers (CV-1 and CV-2), and the LC16m8 strain of Hashizume.

Selection of the recombinant vaccinia virus can be by any method known in the art, including hybridization techniques (e.g., using polymerase DNA sequences as a hybridization probe), immunological techniques (e.g., assay for binding to antibodies recognizing the encoded polymerase epitope(s)), etc. In a preferred aspect where TK flanking sequences are used in the insertion vector, selection is for TK⁻ recombinants, as described above; screening for the correct recombinant can then be carried out by standard molecular analyses. In many preferred aspects, the method of choice for selection is dictated by the selectable marker in an insertion vector used to generate the recombinant viruses.

The selected recombinant vaccinia virus is then generally plaque-purified, and preferably subjected to standard nucleic acid and protein analyses to verify its identity and purity, and expression of the inserted polymerase.

5.5. Large Scale Growth and Purification of Recombinant Replicable Vesiculoviruses

The recovered recombinant vesiculovirus, after plaque-purification, can then be grown to large numbers, by way of example, as follows. Virus from a single plaque (˜10⁶ pfu) is recovered and used to infect ˜10⁷ cells (e.g., BHK cells), to yield, typically, 10 ml at a titer of 10⁹-10¹⁰ pfu/ml for a total of approximately 10¹¹ pfu. Infection of ˜10¹² cells can then be carried out (with a multiplicity of infection of 0.1), and the cells can be grown in suspension culture, large dishes, or roller bottles by standard methods.

It is noted that recombinant vesiculoviruses which no longer express the extracellular region of the vesiculovirus G protein (which determine host range) and which, instead, express an envelope glycoprotein of a different virus will need to be grown in cells which are susceptible to infection by the different virus (and which cells thus express a receptor promoting infection by a virus expressing the envelope glycoprotein of the different virus). Thus, for example, where the recombinant vesiculovirus expresses the HIV envelope glycoprotein, the virus is grown in CD4⁺ cells (e.g., CD4⁺ lymphoid cells).

Virus for vaccine preparations can then be collected from-culture supernatants, and the supernatants clarified to remove cellular debris. If desired, one method of isolating and concentrating the virus that can be employed is by passage of the supernatant through a tangential flow membrane concentration. The harvest can be further reduced in volume by pelleting through a glycerol cushion and by concentration on a sucrose step gradient. An alternate method of concentration is affinity column purification (Daniel et al., 1988, Int. J. Cancer 41:601-608). However, other methods can also be used for purification (see, e.g., Arthur et al., 1986, J. Cell. Biochem. Suppl. 10A:226), and any possible modifications of the above procedure will be readily recognized by one skilled in the art. Purification should be as gentle as possible, so as to maintain the integrity of the virus particle.

5.6. Recombinant Replicable Vesiculoviruses for Use as Live Vaccines

In one embodiment of the invention, the recombinant replicable vesiculoviruses that express an immunogenic Antigen are used as live vaccines.

The recombinant vesiculoviruses for use as therapeutic or prophylactic live vaccines according to the invention are preferably somewhat attenuated. Most available strains e.g., laboratory strains of VSV, may be sufficiently attenuated for use. Should additional attenuation be desired, e.g., based on pathogenicity testing in animals, attenuation is most preferably achieved simply by laboratory passage of the recombinant vesiculovirus (e.g., in BHK or any other suitable cell line). Generally, attenuated viruses are obtainable by numerous methods known in the art including but not limited to chemical mutagenesis, genetic insertion, deletion (Miller, 1972, Experiments in Molecular Genetics, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.) or recombination using recombinant DNA methodology (Maniatis et al., 1982, Molecular Cloning, A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.), laboratory selection of natural mutants, etc.

In this embodiment of the invention, a vaccine is formulated in which the immunogen is one or several recombinant vesiculovirus(es), in which the foreign RNA in the genome directs the production of an Antigen in a host so as to elicit an immune (humoral and/or cell mediated) response in the host that is prophylactic or therapeutic. In an embodiment wherein the Antigen displays the antigenicity or immunogenicity of an antigen of a pathogen, administration of the vaccine is carried out to prevent or treat an infection by the pathogen and/or the resultant infectious disorder and/or other undesirable correlates of infection.

In an embodiment wherein the Antigen is a tumor antigen, administration of the vaccine is carried out to prevent or treat tumors (particularly, cancer).

In a preferred specific embodiment, the recombinant vesiculoviruses are administered prophylactically, to prevent/protect against infection and/or infectious diseases or tumor (e.g., cancer) formation.

In a specific embodiment directed to therapeutics, the recombinant vesiculoviruses of the invention, encoding immunogenic epitope(s), are administered therapeutically, for the treatment of infection or tumor formation. Administration of such viruses, e.g., to neonates and other human subjects, can be used as a method of immunostimulation, to boost the host's immune system, enhancing cell-mediated and/or humoral immunity, and facilitating the clearance of infectious agents or tumors. The viruses of the invention can be administered alone or in combination with other therapies (examples of anti-viral therapies, including but not limited to α-interferon and vidarabine phosphate; examples of tumor therapy including but not limited to radiation and cancer chemotherapy).

5.7. Inactivated Recombinant Vesiculoviruses for Vaccine Use

In a specific embodiment, the recombinant replicable vesiculoviruses of the invention are inactivated (i.e., killed, rendered nonreplicable) prior to vaccine use, to provide a killed vaccine. Since the vesiculovirus envelope is highly immunogenic, in an embodiment wherein one or more foreign proteins (e.g., an envelope glycoprotein of a virus other than a vesiculovirus) is incorporated into the vesiculovirus envelope, such a virus, even in killed form, can be effective to provide an immune response against said foreign protein(s) in a host to which it is administered. In a specific embodiment, a multiplicity of Antigens, each displaying the immunogenicity or antigenicity of an envelope glycoprotein of a different virus, are present in the recombinant vesiculovirus particle.

The inactivated recombinant viruses of the invention differ from defective interfering particles in that, prior to inactivation the virus is replicable (i.e., it encodes all the vesiculovirus proteins necessary to enable it to replicate in an infected cell). Thus, since the virus is originally in a replicable state, it can be easily propagated and grown to large amounts prior to inactivation, to provide a large amount of killed virus for use in vaccines, or for purification of the expressed antigen for use in a subunit vaccine (see Section 5.8, infra).

Various methods are known in the art and can be used to inactivate the recombinant replicable vesiculoviruses of the invention, for use as killed vaccines. Such methods include but are not limited to inactivation by use of formalin, betapropiolactone, gamma irradiation, and psoralen plus ultraviolet light.

In a specific embodiment, recombinant vesiculovirus can be readily inactivated by resuspension of purified virions in a suitable concentration of formaldehyde. While 0.8 formaldehyde may be sufficient, verification of the optimum concentration of formaldehyde can be readily determined for a particular virus by titration of serial dilutions of formaldehyde with infectious virus to determine the inactivation curve of formalin for that virus. This technique has been described in detail by Salk and Gori, 1960, Ann. N.Y. Acad. Sci. 83:609-637). By extrapolation to zero, the concentration expected to inactivate the last infectious particle can be estimated. By utilizing a substantially higher concentration, e.g., 4-fold greater than the estimated concentration, complete inactivation can be assured.

Although formalin inactivation alone has proven to be effective, it may be desirable, for safety and regulatory purposes, to kill the virus twice or more, using one or more of the numerous other methods currently known for virus inactivation. Thus, although not essential, it is contemplated that the virus used in the final formulation will be often inactivated by a second agent after treatment with formalin.

5.8. Use of Recombinant Replicable Vesiculoviruses in the Production of Subunit Vaccines

Since the recombinant vesiculoviruses of the invention can be propagated and grown to large amounts, where the recombinant vesiculoviruses express an Antigen, growth of such vesiculoviruses provides a method for large scale production and ready purification of the expressed Antigen, particularly when the Antigen is incorporated into the envelope of the recombinant vesiculovirus. In a specific embodiment, the Antigen is all or a portion of an envelope glycoprotein of another virus, e.g., HIV gp160, expressed as a nonfusion protein, or expressed as a fusion to the cytoplasmic domain of a vesiculovirus G protein.

The Antigens thus produced and purified have use in subunit vaccines.

The recombinant vesiculoviruses that express an Antigen can also be used to recombinantly produce the Antigen in infected cells in vitro, to provide a source of Antigen for use in immunoassays, e.g., to detect or measure in a sample of body fluid from a vaccinated subject the presence of antibodies to the Antigen, and thus to diagnose infection or the presence of a tumor and/or monitor immune response of the subject subsequent to vaccination.

5.9. Determination of Vaccine Efficacy

Immunopotency of the one or more Antigen(s) in its live or inactivated vesiculovirus vaccine formulation, or in is subunit vaccine formulation, can be determined by monitoring the immune response of test animals following immunization with the recombinant vesiculovirus(es) expressing the Antigen(s) or with the subunit vaccine containing the Antigen, by use of any immunoassay known in the art. Generation of a humoral (antibody) response and/or cell-mediated immunity, may be taken as an indication of an immune response. Test animals may include mice, hamsters, dogs, cats, monkeys, rabbits, chimpanzees, etc., and eventually human subjects.

Methods of introduction of the vaccine may include oral, intracerebral, intradermal, intramuscular, intraperitoneal, intravenous, subcutaneous, intranasal or any other standard routes of immunization. The immune response of the test subjects can be analyzed by various approaches such as: the reactivity of the resultant immune serum to the Antigen, as assayed by known techniques, e.g., enzyme linked immunosorbent assay (ELISA), immunoblots, radioimmunoprecipitations, etc.; or, in the case where the Antigen displays the antigenicity or immunogenicity of a pathogen's antigen, by protection of immunized hosts from infection by the pathogen and/or attenuation of symptoms due to infection by the pathogen in immunized hosts; or, in the case where the antigen displays the antigenicity or immunogenicity of a tumor antigen, by prevention of tumor formation or prevention of metastasis, or by regression, or by inhibition of tumor progression, in immunized hosts.

As one example of suitable animal testing of a live vaccine, live vaccines of the invention may be tested in rabbits for the ability to induce an antibody response to the Antigens. Male specific-pathogen-free (SPF) young adult New Zealand White rabbits may be used. The test group of rabbits each receives approximately 5×10⁸ pfu (plaque forming units) of the vaccine. A control group of rabbits receives an injection in 1 mM Tris-HCl pH 9.0 of a non-recombinant vesiculovirus or of a recombinant vesiculovirus which does not express the same Antigen.

Blood samples may be drawn from the rabbits every one or two weeks, and serum analyzed for antibodies to the Antigen(s). The presence of antibodies specific for the Antigen(s) may be assayed, e.g., using an ELISA.

Animals may also be used to test vaccine efficacy (e.g., challenge experiments). For example, in a specific embodiment regarding a live vaccine formulation, monkeys each receive intradermally approximately 5×10⁸ pfu of recombinant vesiculovirus. A control monkey receives (control) non-recombinant virus intradermally. Blood is drawn weekly for 12 weeks, and serum is analyzed for antibodies to the Antigen(s).

5.10. Vaccine Formulation and Administration

The vaccines of the invention may be multivalent or univalent. Multivalent vaccines are made from recombinant viruses that direct the expression of more than one Antigen, from the same or different recombinant viruses.

Many methods may be used to introduce the vaccine formulations of the invention; these include but are not limited to oral, intradermal, intramuscular, intraperitoneal, intravenous, subcutaneous, intranasal routes, and via scarification (scratching through the top layers of skin, e.g., using a bifurcated needle).

The patient to which the vaccine is administered is preferably a mammal, most preferably a human, but can also be a non-human animal including but not limited to cows, horses, sheep, pigs, fowl (e.g., chickens), goats, cats, dogs, hamsters, mice and rats. In the use of a live vesiculovirus vaccine, the patient can be any animal in which vesiculovirus replicates (for example, the above-listed animals).

The virus vaccine formulations of the invention comprise an effective immunizing amount of one or more recombinant vesiculoviruses (live or inactivated, as the case may be) and a pharmaceutically acceptable carrier or excipient. Subunit vaccines comprise an effective immunizing amount of one or more Antigens and a pharmaceutically acceptable carrier or excipient. Pharmaceutically acceptable carriers are well known in the art and include but are not limited to saline, buffered saline, dextrose, water, glycerol, sterile isotonic aqueous buffer, and combinations thereof. One example of such an acceptable carrier is a physiologically balanced culture medium containing one or more stabilizing agents such as stabilized, hydrolyzed proteins, lactose, etc. The carrier is preferably sterile. The formulation should suit the mode of administration.

The composition, if desired, can also contain minor amounts of wetting or emulsifying agents, or pH buffering agents. The composition can be a liquid solution, suspension, emulsion, tablet, pill, capsule, sustained release formulation, or powder. Oral formulation can include standard carriers such as pharmaceutical grades of mannitol, lactose, starch, magnesium stearate, sodium saccharine, cellulose, magnesium carbonate, etc.

Generally, the ingredients are supplied either separately or mixed together in unit dosage form, for example, as a dry lyophilized powder or water free concentrate in a hermetically sealed container such as an ampoule or sachette indicating the quantity of active agent. Where the composition is administered by injection, an ampoule of sterile diluent can be provided so that the ingredients may be mixed prior to administration.

In a specific embodiment, a lyophilized recombinant vesiculovirus of the invention is provided in a first container; a second container comprises diluent consisting of an aqueous solution of 50% glycerin, 0.25% phenol, and an antiseptic (e.g., 0.005% brilliant green).

The precise dose of virus, or subunit vaccine, to be employed in the formulation will also depend on the route of administration, and the nature of the patient, and should be decided according to the judgment of the practitioner and each patient's circumstances according to standard clinical techniques. An effective immunizing amount is that amount sufficient to produce an immune response to the Antigen in the host to which the recombinant vesiculovirus, or subunit vaccine, is administered.

In a specific embodiment, an effective immunizing amount of a live recombinant vesiculovirus of the present invention is within the range of 10³ to 10⁹ pfu/dose, more preferably 10⁶ to 10⁹ pfu/dose. Boosting is possible but not preferred. If boosting is desired, one optionally may boost with the Antigen in purified form rather than using a recombinant vesiculovirus of the invention.

For inactivated recombinant vesiculovirus vaccines, the vaccine formulation comprises an effective immunizing amount of the inactivated virus, preferably in combination with an immunostimulant; and a pharmaceutically acceptable carrier. As used in the present context, “immunostimulant” is intended to encompass any compound or composition which has the ability to enhance the activity of the immune system, whether it be a specific potentiating effect in combination with a specific antigen, or simply an independent effect upon the activity of one or more elements of the immune response. Some of the more commonly utilized immunostimulant compounds in vaccine compositions are the adjuvants alum or muramyl dipeptide (MDP) and its analogues. Methods of utilizing these materials are known in the art, and it is well within the ability of the skilled artisan to determine an optimum amount of stimulant for a given virus vaccine. It may also be desired to use more than one immunostimulant in a given formulation.

The exact amount of inactivated virus utilized in a given preparation is not critical, provided that the minimum amount of virus necessary to provoke an immune response is given. A dosage range of as little as about 10 μg, up to amount a milligram or more, is contemplated. As one example, in a specific embodiment, individual dosages may range from about 50-650 μg per immunization.

Use of purified Antigens as subunit vaccines can be carried out by standard methods. For example, the purified protein(s) should be adjusted to an appropriate concentration, formulated with any suitable vaccine adjuvant and packaged for use. Suitable adjuvants may include, but are not limited to: mineral gels, e.g., aluminum hydroxide; surface active substances such as lysolecithin, pluronic polyols; polyanions; peptides; oil emulsions; alum, and MDP. The immunogen may also be incorporated into liposomes, or conjugated to polysaccharides and/or other polymers for use in a vaccine formulation. In instances where the recombinant Antigen is a hapten, i.e., a molecule that is antigenic in that it can react selectively with cognate antibodies, but not immunogenic in that it cannot elicit an immune response, the hapten may be covalently bound to a carrier or immunogenic molecule; for instance, a large protein such as serum albumin will confer immunogenicity to the hapten coupled to it. The hapten-carrier may be formulated for use as a vaccine.

Effective doses (immunizing amounts) of the vaccines of the invention may also be extrapolated from dose-response curves derived from animal model test systems.

The invention also provides a pharmaceutical pack or kit comprising one or more containers comprising one or more of the ingredients of the vaccine formulations of the invention. Associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use or sale for human administration.

The present invention thus provides a method of immunizing an animal, or treating or preventing various diseases or disorders in an animal, comprising administering to the animal an effective immunizing dose of a vaccine of the present invention.

5.11. Use of Antibodies Generated by the Vaccines of the Invention

The antibodies generated against the Antigen by immunization with the recombinant viruses of the present invention also have potential uses in diagnostic immunoassays, passive immunotherapy, and generation of antiidiotypic antibodies.

The generated antibodies may be isolated by standard techniques known in the art (e.g., immunoaffinity chromatography, centrifugation, precipitation, etc.) and used in diagnostic immunoassays. The antibodies may also be used to monitor treatment and/or disease progression. Any immunoassay system known in the art, such as those listed supra, may be used for this purpose including but not limited to competitive and noncompetitive assay systems using techniques such as radioimmunoassays, ELISA (enzyme-linked immunosorbent assays), “sandwich” immunoassays, precipitin reactions, gel diffusion precipitin reactions, immunodiffusion assays, agglutination assays, complement-fixation assays, immunoradiometric assays, fluorescent immunoassays, protein A immunoassays and immunoelectrophoresis assays, to name but a few.

The vaccine formulations of the present invention can also be used to produce antibodies for use in passive immunotherapy, in which short-term protection of a host is achieved by the administration of pre-formed antibody directed against a heterologous organism.

The antibodies generated by the vaccine formulations of the present invention can also be used in the production of antiidiotypic antibody. The antiidiotypic antibody can then in turn be used for immunization, in order to produce a subpopulation of antibodies that bind the initial antigen of the pathogenic microorganism (Jerne, 1974, Ann. Immunol. (Paris) 125c:373; Jerne, et al., 1982, EMBO J. 1:234).

6. Recombinant Vesicular Stomatitis Viruses from DNA

We assembled a DNA clone containing the 11,161 nucleotide sequence of the prototype rhabdovirus, vesicular stomatitis virus (VSV), such that it could be transcribed by the bacteriophage T7 RNA polymerase to yield a full-length positive strand RNA complementary to the VSV genome. Expression of this RNA in cells also expressing the VSV nucleocapsid protein and the two VSV polymerase subunits resulted in production of VSV with the growth characteristics of wild-type VSV. Recovery of virus from DNA was verified by: 1) the presence of two genetic tags generating novel restriction sites in DNA derived from the genome; 2) direct sequencing of the genomic RNA of the recovered virus, and 3), production of a VSV recombinant in which the glycoprotein was derived from a second serotype. The ability to generate VSV from DNA opens numerous possibilities for the genetic analysis of VSV replication. In addition, because VSV can be grown to very high titers and in large quantities with relative ease, one can genetically engineer recombinant VSVs displaying novel antigens. Such modified viruses can be used as vaccines conferring protection against other viruses or pathogenic microorganisms, or to produce immunity in general against an encoded foreign antigen.

6.1. Materials and Methods

Plasmid Construction. The plasmid pVSVFL(+) expressing the 11,161 nucleotide positive strand (antigenomic) VSV RNA sequence was constructed from four DNA fragments cloned into pBluescript SK⁺ (Stratagene). The starting plasmid for the construction, pVSVFL(−), expressed the complete negative sense VSV genomic RNA (Indiana serotype) from a T7 promoter. This plasmid was generated in a nine step cloning procedure that involved joining the five original cDNA clones of the VSV mRNAs (Gallione et al., 1981, J. Virol. 39:529-535; Rose and Gallione, 1981, J. Virol. 39:519-528; Schubert et al., 1985, Proc. Natl. Acad. Sci. USA 82:7984-7988) with gene junction fragments and terminal fragments. These fragments were generated by reverse transcription and polymerase chain reaction (RT-PCR) (Mullis and Faloona, 1987, Methods in Enzymology 155:335-350) from VSV genomic RNA (M. A. Whitt, R. Burdine, E. A. Stillman and J. K. Rose, manuscript in preparation). To facilitate engineering of the VSV genome and to provide genetic tags, unique Mlu I and Nhe I restriction enzyme sites were introduced by oligonucleotide-directed mutagenesis into the 5′ and 3′ non-coding regions flanking the VSV glycoprotein gene prior to construction of the full length genome.

In the initial step of constructing pVSVFL(+) we used the primers (5′CCGGCTCGAGTTGTAATACGACTCACTATAGGGACGAAGACAAACAAACCATTATTAT C-3′) (SEQ ID NO:38) and (5′GAACTCTCCTCTAGATGAGAAC-3′) (SEQ ID NO:39) to amplify (Mullis and Faloona, 1987, Methods in Enzymology 155:335-350) a 2,124 nucleotide fragment from pVSVFL(−) (# 1, FIG. 4A). This fragment corresponds to the 3′ end of the VSV genome. The first primer introduced an Xho I site and a T7 promoter (underlined) immediately preceding the sequence complementary to the 3′ end of the VSV genome. The second primer covered a unique Xba I site present in the VSV P gene. The PCR product was digested with Xho I and Xba I and cloned into pBluescript SK⁺ (Stratagene) that had been digested with Xho I and Xba I. The resulting plasmid carrying the sequence corresponding to the 3′ end of the VSV genome preceded by a T7 promoter was designated pBSXX. Note that an additional T7 promoter is also present upstream of the Xho I site in the vector. Next we generated the sequence corresponding to the 5′ end of the VSV genome and part of the hepatitis delta virus (HDV) ribozyme (Pattnaik et al., 1992, Cell 69:1011-1120; Perrotta and Been, 1991, Nature 350:434-436). A 147 nucleotide PCR product (#3, FIG. 4A) was amplified from pVSVFL(−) with primers (5′AGGTCGGACCGCGAGGAGGTGGAGATGCCATGCCGACCCACGAAGACCACAAAACCAG-3′) (SEQ ID NO:40) and (5′ATGTTGAAGAGTGACCTACACG-3′) (SEQ ID NO:41). The first primer contained 39 nucleotides of the sequence encoding the HDV ribozyme (underlined) followed by 19 nucleotides complementary to the 3′ end of the VSV antigenomic RNA. The second primer hybridized within the L gene (FIG. 4A). The PCR product was digested with Afl II and Rsr II and the 80 nucleotide Afl II-Rsr II fragment was ligated to a 225 nucleotide Rsr II-Sac I fragment (#4, FIG. 4A) derived from a plasmid designated pBS-GMG (Stillman et al., manuscript submitted). Fragment 4 contained the T7 terminator sequence and the remainder of the sequence encoding the HDV ribozyme. Ligated products were digested with Afl II and Sac I and the 305 nucleotide Afl II-Sac I product was cloned into the Afl II and Sac I sites of a modified pBSXX vector that contained an Afl II site inserted at the unique Not I site within the polylinker. This plasmid containing the Afl II-Sac I fragment was designated pBXXAS. To complete the construction, a 10,077 nucleotide Bst 1107 I to Afl II fragment (#2, FIG. 4A) containing 90% of the VSV sequences from pVSVFL(−) was inserted into the unique Bst 1107 I and AflII sites of pBXXAS. The final plasmid was designated pVSVFL(+). The sequences in this plasmid generated by PCR (hatched sequences, FIG. 4B) were determined and contained no errors. We also prepared a plasmid in which the sequence of the VSV Indiana serotype G gene (MluI-NheI) was replaced with the G gene from the New Jersey serotype of VSV (Gallione and Rose, 1983, J. Virol. 46:162-169). This plasmid is called pVSVFL(+)_(I/NJG) and has only a single T7 promoter.

Transfection and recovery of recombinant VSV. Baby hamster kidney cells (BHK-21, ATCC) were maintained in DME (Dulbecco's modified Eagle's medium) supplemented with 5% fetal bovine serum (FBS). Cells on 10 cm dishes (˜70% confluent) were infected at a multiplicity of 10 with vTF7-3 (Fuerst et al., 1986, Proc. Natl. Acad. Sci. USA 83:8122-8126). After 30 min, plasmids encoding the VSV antigenomic RNA and the N, P, and L proteins were transfected into the cells using a calcium phosphate transfection kit according to directions supplied (Stratagene). The coding regions for N, P, and L proteins were each expressed in pBluescript SK(+) from the T7 promoter. Plasmid amounts were 10 μg pVSVFL(+), 5 μg pBS-N, 4 μg pBS-P, and 2 μg pBS-L. After 24-48 h incubation at 37° C. in 3% CO₂, cells were scraped from the dish and subjected to three rounds of freeze-thawing (−70° C., 37° C.) to release cell-associated virus. Debris was pelleted from the cell lysates by centrifugation at 1,250×g for 5 min. Five ml of this lysate was added to approximately 10⁶ BHK cells on a 10 cm plate in 10 ml of DME+5% FBS. After 48 h the medium was clarified by centrifugation at 1,250×g for 10 min, and passed through a filter to remove the majority of the vaccinia virus (0.2 μm pore size, Gelman Sciences). One ml was then added directly to BHK cells that had been plated on a coverslip in a 35 mm dish. After four hours, the cells were fixed in 3% paraformaldehyde and stained with monoclonal antibody I1 to the VSV G_(I) protein (Lefrancois and Lyles, 1982, Virology 121:168-174) or 9B5 (Bricker et al., 1987, Virology 161:533-540) to the VSV G_(NJ) protein followed by goat anti-mouse rhodamine conjugated antibody (Jackson Research). Cells were then examined by indirect immunofluorescence using a Nikon Microphot-FX microscope equipped with a 40× planapochromat objective. When VSV recovery was successful, 100% of the cells showed the typical bright stain for G protein characteristic of a VSV infection.

Preparation and analysis of VSV RNA and protein. Recombinant VSV and wild-type VSV isolated from single plaques (˜10⁵ plaque forming units) were used to infect a monolayer of BHK cells (˜80% confluent) on a 10 cm dish in 10 ml DME plus 5% FBS. After 24 h, cell debris and nuclei were removed by centrifugation at 1,250×g for 5 min, and virus was then pelleted from the medium at 35,000 RPM in a Beckman SW41 rotor for one hour. Virus pellets were resuspended in 0.5 ml 10 mM Tris-HCl, pH 7.4 for protein analysis. For RNA isolation, virus was resuspended in 0.2 ml of 0.5% SDS/0.2M sodium acetate, pH 8.0, followed by extraction with phenol/CHCl₃. RNA was precipitated with 95% ethanol and 5 μg carrier tRNA. RNA was pelleted by centrifugation at 12,000×g for 15 min and resuspended in water with 1 unit RNasin (Promega). For analysis of RNA by RT-PCR, primer pairs flanking either the novel Nhe I or Mlu I sites were used. The first strand DNA synthesis reaction was carried out in 50 μl of PCR buffer (Promega) containing 5 mM MgCl₂, 1 mM dNTPs, 1 unit RNAs in (Promega), 1 unit avian myeloblastosis virus reverse transcriptase (AMV RT; Promega) 0.75 μM primer and approximately 0.25 μg of VSV genomic RNA. Incubation was at 42° C. for 15 min followed by 5 min at 99° C. and 5 min at 5° C. PCR was carried out by addition of 0.5 U Taq polymerase, adjustment of MgCl₂ concentration to 1.25 mM, and addition of the second primer (0.75 μM). The reaction was subjected to 20 thermal cycles: 95° C., 1 min; 60° C. 1.5 min. The reaction was then incubated at 60° C. for 7 min.

Direct sequencing of VSV genomic RNA was performed according to a previously described protocol based on the dideoxy chain termination method (Mierendorf and Pfeffer, 1987, Methods in Enzymology 152:563-566) except that [α-³³P]dATP (Amersham, Inc.) was used. Each reaction included approximately 0.25 μg of VSV genomic RNA.

6.2. Results

To construct a cDNA clone encoding the entire 11,161 VSV genome, individual cDNA clones of the VSV mRNAs were initially joined using small DNA fragments generated by RT-PCR that covered the four gene junctions. Correct genomic terminal sequences were also generated by RT-PCR of the VSV genome, and these were joined to the other DNAs using restriction sites. This initial clone was constructed with a T7 promoter directing synthesis of the full-length negative strand VSV RNA. Despite numerous attempts, we were unable to recover VSV from cells expressing the VSV genomic RNA and the VSV N, P, and L proteins. The VSV constructed was thus redesigned to express the VSV antigenomic DNA. The construction strategy is described in Materials and Methods and in FIG. 4A-B. The entire VSV sequence as well as a T7 promoter, terminator and HDV ribozyme sequence were cloned in pBluescript SK+ between the Xho I and Sac I sites (FIG. 4B; FIG. 1). An additional T7 promoter is also present upstream of the Xho I site in the plasmid. A slightly different cloning strategy was used to generate plasmids lacking the upstream T7 promoter and VSV has also been recovered from these constructs.

Recovery of VSV from DNA. To determine if we could recover VSV from plasmid DNA, we infected cells with vaccinia vTF7-3 (Fuerst et al., 1986, Proc. Natl. Acad. Sci. USA 83:8122-8126) to provide cytoplasmic T7 RNA polymerase. These cells were then transfected with pVSVFL(+), which expresses the antigenomic VSV RNA from a T7 promoter, and three other plasmids which express the VSV N, P, and L proteins. Expression of the N protein was required to assemble nascent VSV antigenomic RNA into nucleocapsids. Once formed, these nucleocapsids should serve as templates for synthesis of minus strand RNA by the L/P polymerase complex. Encapsidated minus strand RNA should then be a template for transcription, initiating the VSV infectious cycle.

The initial recovery experiment employed two 10 cm plates of BHK cells (˜5×10⁶ cells each). At 24 hours after the infection with vTF7-3 and transfection with the four plasmids, cells and medium were frozen and thawed to release any cell-associated VSV, and the clarified lysates were added to fresh BHK cells. After 48 hours, both plates showed severe cytopathic effects that could have been due either to vaccinia virus or to recovered VSV. One ml of each supernatant was then added to small dishes of BHK cells on coverslips. After two hours, one of these coverslips showed rounded cells characteristic of a VSV infection, while the other did not. After 4 hours, cells on both coverslips were fixed, stained with appropriate antibodies, and examined by indirect immunofluorescence microscopy to detect the VSV G protein. All cells on the coverslip showing rounded cells revealed intense fluorescence characteristic of G protein expression during VSV infection (data not shown). Subsequent passaging and analysis described below showed that VSV had been recovered from the transfection. The other coverslip showed no G expression, and no VSV could be recovered after passaging.

Based on the frequency with which rabies virus (Schnell et al., 1994, EMBO J. 13:4195-4203) and VSV minigenomes (Stillman et al., manuscript submitted) were recovered, we anticipated that recovery of complete VSV, if obtainable, would be a rare event. The initial recovery of VSV from only one of two transfections suggested the possibility that the initial titer in the positive lysate was very low. To examine this titer, we infected BHK cells on coverslips with one tenth of the lysate (1 ml) derived from each initial transfection. After eight hours, the cells were examined for expression of G protein by indirect immunofluorescence. A scan of the entire coverslip revealed no VSV infection from the negative lysate, and only five small areas of infection (2-6 cells each) from the lysate that gave rise to VSV G expression on subsequent passaging. The initial titer was therefore very low as we suspected, and likely represented a total of about 50 infectious particles, probably derived from a VSV infection initiated in only one cell out of 2×10⁷ transfected. This low rate of recovery of infectious VSV is typical of that observed in several experiments.

Analysis of viral proteins. Subsequent passages and plaque assays of VSV recovered in three independent experiments revealed plaques that were detectable in less than 16 hours and titers up to 2×10⁹pfu/ml characteristic of VSV. For further verification that VSV had been recovered, the proteins in virus pelleted from the medium were examined by SDS polyacrylamide gel electrophoresis (PAGE). FIG. 5 shows the Coomassie stained gel of proteins of VSV recovered from recombinant DNA (rVSV) and wildtype VSV. The mobilities and relative amounts of the five viral proteins were indistinguishable in the wildtype and recombinant virus.

Identification of sequence tags. In pVSVFL(+), the VSV nucleotide sequence was altered by oligonucleotide-directed mutagenesis to generate unique Mlu I and Nhe I restriction enzyme sites in the 5′ and 3′ non-coding regions of the glycoprotein gene. To verify that these sites were present in recovered virus, we carried out reverse transcription of genomic RNA purified from wild-type or recombinant virions using primers upstream of each restriction site. The reverse transcription products were then amplified by PCR using an additional primer downstream of each restriction site. The presence of the genetic tag in the recombinant virus was verified by digestion of the PCR products with the appropriate restriction enzymes. Using this method, the presence of both the Mlu I and Nhe I sequences in the recovered virus RNA was verified, and the results for the Nhe I site are shown in FIG. 6. Sequences from wild-type VSV and recombinant VSV were amplified in parallel and a 620 nucleotide fragment was obtained in both cases (lanes 3 and 5). No product was obtained when reverse transcriptase was omitted from the reactions prior to PCR (lanes 1 and 2), indicating that the PCR product was derived from RNA, not from contaminating DNA. After digestion with Nhe I, expected fragments of 273 and 347 base pairs were obtained from recombinant VSV RNA, while the DNA derived from the wildtype RNA remained undigested (lanes 4 and 6).

Direct sequencing of tagged genomic RNA. The presence of new restriction sites in the DNA generated by PCR provided strong evidence that VSV had been recovered from DNA. To ensure that identification of the genetic tags by PCR had not resulted from inadvertent contamination by plasmid DNA, we carried out direct sequence analysis of the genomic RNA using reverse transcriptase and a primer hybridizing upstream of the Nhe I site. The sequence from the autoradiogram shown in FIG. 7 is in exact agreement with the published sequence of the VSV G mRNA (Rose and Gallione, 1981, J. Virol. 39:519-528) except that the four nucleotide changes used to generate the Nhe I site (GCACAA to GCTAGC) are present. These results show unequivocally that the sequence tag is present in the genomic RNA.

Recombinant VSV Indiana virus carrying the glycoprotein of the New Jersey serotype. There are two serotypes of VSV designated Indiana and New Jersey. The glycoproteins of the two serotypes share approximately 50% sequence identity (Gallione and Rose, 1983, J. Virol. 46:162-169). In earlier studies we found that the glycoprotein of the New Jersey serotype could complement a mutant of the VSV_(I) serotype that makes a defective glycoprotein (Whitt et al., 1989, J. Virol. 63:3569-3578). It therefore seemed likely that a recombinant VSV in which the Indiana glycoprotein (G_(I)) gene was replaced by the New Jersey glycoprotein (G_(NJ)) gene would be viable despite the extensive sequence divergence. To generate such a recombinant, the G_(NJ) cDNA was amplified by PCR using primers that introduced Mlu I and Nhe I sites within the 5′ and 3′ non-coding regions at each end of the gene. The amplified DNA was cloned into pBluescript and the G_(NJ) protein was expressed in BHK cells using the vaccinia-T7 system. The protein expressed was shown to have membrane fusion activity below pH 6.0 indicating that it was functional (data not shown). This G_(NJ) cDNA was then cloned into the unique Mlu I and Nhe I sites of the full-length construct after removal of sequences encoding G_(I). Recombinant VSV was recovered essentially as described above except that the initial transfection was allowed to proceed for 48 hours before the freeze-thaw step. After the first passage, expression of the G_(NJ) protein was verified by indirect immunofluorescence using a monoclonal antibody specific to Go (Bricker et al., 1987, Virology 161:533-540). The virus was then plaque purified and grown. To examine the proteins present in the recombinant virus, virus recovered from cells infected with VSV_(I), VSV_(NJ), and the recombinant VSV_(I/NJG) was analyzed by SDS-PAGE followed by Coomassie staining. The VSV_(I) G, N, P, and M proteins each have mobilities distinct from their VSV_(NJ) counterparts (FIG. 8, lanes 1 and 3). The recombinant VSV_(I/NJG) shows the mobility difference in only the G protein as expected (lane 2). The presence of the novel Nhe I and Mlu I sites in the recombinant was also verified (data not shown).

6.3. Discussion

The results presented here establish that infectious VSV can be recovered from recombinant DNA. We believe that expressing the positive strand, antigenomic RNA in the presence of the N, P and L proteins was critical to our success because we have not recovered virus starting with an equivalent construct encoding the genomic RNA.

Why is the initial event of generating VSV so rare, apparently occurring in only 1 in 10⁷ to 10⁸ transfected cells? One possibility is that our clone contains a sequence error that is only corrected by a rare mutational event. We believe this is not the case because the clone was completely sequenced prior to assembly and differences from published sequences were corrected, or the proteins were shown to be functional in complementation assays. Also, the frequency of recovery is actually higher than expected based on our observations with minigenomes encoding one or two VSV proteins (Stillman et al., manuscript submitted). In these cases we found that a transcribing and replicating minigenome (˜2 kb RNA) was recovered in about 1 in 10² transfected cells expressing the RNA with the N,P and L proteins. Addition of a second cistron (0.85 kb additional RNA) encoding the M protein dropped the recovery rate to approximately 1 in 10³ transfected cells. If there is a ten-fold drop in recovery rate for each additional kilobase of RNA added, one can easily rationalize an even lower frequency of recovery for the 11, 161 kb genome than we observed. Although these minigenomes encode negative sense RNAs, the comparison of the frequency of recovery to that of the full length plus construct is probably valid because expression of the N, P and L mRNAs would not generate mRNAs complementary to the minigenome.

Although the rate limiting step in generation of infectious VSV is not known, it is likely to be at the level of synthesis and encapsidation of the large antigenomic RNA, which must occur prior to replication and transcription. The complete encapsidation with N protein probably has to occur on the nascent RNA to protect it from degradation, and the cells in which this occurs must also produce appropriate amounts of L and P proteins to initiate replication. Once this has occurred, however, the transcription and translation of the genome should generate additional N, P, and L proteins as well as the G and M proteins required for budding of infectious virus.

The recovery of VSV from DNA opens numerous aspects of the viral life cycle to genetic analysis. The studies of the genetic signals involved in transcription and replication have so far been confined to analysis of defective RNAs that do not encode viral proteins (Pattnaik et al., 1992, Cell 69:1011-1120; Wertz et al., 1994, Proc. Natl. Acad. Sci. USA 91:8587-8591). These and other signals can be now examined in the context of a VSV infection occurring in the absence of a vaccinia virus infection. The system we have described also provides an opportunity to study the roles of individual viral protein domains and modifications in viral assembly and replication. Previously these analyses have been confined to in vitro systems or to analysis employing the complementation of naturally occurring mutants where synthesis of the mutant protein can complicate the analysis.

Perhaps even more exciting is the ability to use VSV as a vector to express other proteins. The experiment in which we recovered VSV Indiana carrying the glycoprotein from the New Jersey serotype (FIG. 8) illustrates that viable recombinants can be made. For reasons that are unclear the titers of recombinant virus were at least ten-fold lower than those obtained with either parent. The lower titer apparently did not result from a defect in viral assembly because the amounts of proteins in wildtype and recombinant virions at the end of the infection were comparable (FIG. 8). Our previous experiments showed that a foreign glycoprotein carrying the appropriate cytoplasmic tail signal could be incorporated into the VSV envelope (Owens and Rose, 1993, J. Virol. 67:360-365). This suggests that one may generate recombinant VSVs carrying novel proteins in their envelopes. If these were appropriately attenuated, they can be used as vaccines against other viral diseases.

The truncated genomes of defective interfering particles are replicated and packaged very well, thus we suspect that there will be flexibility in the maximum length of the genome that can be packaged as well. Presumably a longer nucleocapsid can be packaged as a longer bullet-shaped particle. Because of the modular nature of the VSV genome, with conserved gene end and start sequences at the gene junctions (Rose and Schubert, 1987, in The Viruses: The Rhabdoviruses, Plenum Publishing Corp., NY, pp. 129-166), it should be relatively easy to engineer additional genes into VSV.

7. Deposit of Microorganisms

Plasmid pVSVFL(+) was deposited on May 2, 1995 with the American Type Culture Collection (ATCC), 1201 Parklawn Drive, Rockville, Md. 20852, under the provisions of the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Purposes of Patent Procedures, and assigned accession no. ______.

The present invention is not to be limited in scope by the microorganism deposited or the specific embodiments described herein. Indeed, various modifications of the invention in addition to those described herein will become apparent to those skilled in the art from the foregoing description and accompanying figures. Such modifications are intended to fall within the scope of the appended claims.

Various publications are cited herein, the disclosures of which are incorporated by reference in their entireties. 

1-43. (canceled)
 44. A kit comprising in one or more containers (a) a first recombinant nucleic acid that can be transcribed in a host cell to produce an RNA molecule comprising a vesiculovirus antigenomic (+) RNA, in which a foreign RNA sequence is inserted into or replaces a region of the RNA nonessential for replication of the vesiculovirus (b) a second recombinant nucleic acid encoding and capable of expressing in the host cell a vesiculovirus N protein; (c) a third recombinant nucleic acid encoding and capable of expressing in the host cell a vesiculovirus L protein; and (d) a fourth recombinant nucleic acid encoding and capable of expressing in the host cell a vesiculovirus P protein.
 45. A kit comprising in one or more containers (a) a first recombinant nucleic acid that can be transcribed in a host cell to produce an RNA molecule comprising a vesiculovirus antigenomic (+) RNA; (b) a second recombinant nucleic acid encoding and capable of expressing in the host cell a vesiculovirus N protein; (c) a third recombinant nucleic acid encoding and capable of expressing in the host cell a vesiculovirus L protein; and (d) a fourth recombinant nucleic acid encoding and capable of expressing in the host cell a vesiculovirus P protein.
 46. A kit comprising in one or more containers (a) a recombinant nucleic acid that can be transcribed to produce an RNA molecule comprising a vesiculovirus antigenomic (+) RNA; and (b) a host cell that recombinantly expresses vesiculovirus N, P, and L proteins.
 47. The kit of claim 45 in which said first recombinant nucleic acid further comprises a polylinker in a region that is transcribed to produce said RNA molecule, said region being nonessential for replication of the vesiculovirus.
 48. The kit according to claim 45 in which the second recombinant nucleic acid is a DNA plasmid vector comprising the following operatively linked components: (a) a promoter which controls the expression of the N protein; (b) a translation initiation signal; (c) a DNA sequence encoding the N protein; and (d) a transcription termination signal; and in which the third recombinant nucleic acid is a DNA plasmid vector comprising the following operatively linked components: (a) a promoter which controls the expression of the P protein; (b) a translation initiation signal; (c) a DNA sequence encoding the P protein; and (d) a transcription termination signal and in which the fourth recombinant nucleic acid is a DNA plasmid vector comprising the following operatively linked components: (a) a promoter which controls the expression of the L protein; (b) a translation initiation signal; (c) a DNA sequence encoding the L protein; and (d) a transcription termination signal; and in which the first recombinant nucleic acid is a DNA plasmid vector comprising the following operatively linked components: (a) a promoter; (b) a DNA sequence that can be transcribed under the control of the promoter in the cell to produce said RNA molecule, said RNA molecule further comprising a ribozyme sequence immediately downstream of said antigenomic (+) RNA, that cleaves at the 3′ terminus of the antigenomic (+) RNA, said DNA comprising a polylinker in a region that is transcribed to produce said RNA molecule, said region being nonessential for replication of the vesiculovirus; and (c) a transcription termination signal.
 49. The kit of claim 48 in which the promoter is an RNA polymerase promoter, and in which the cell also contains a cytoplasmic source of said RNA polymerase.
 50. A kit comprising (a) in a first container a first DNA plasmid vector comprising the following operatively linked components: (i) a bacteriophage RNA polymerase promoter; (ii) a first DNA sequence that can be transcribed in a cell to produce an RNA molecule comprising (A) a vesiculovirus antigenomic (+) RNA in which a foreign RNA sequence is inserted into or replaces a region of the RNA nonessential for replication of the vesiculovirus, and (B) a ribozyme sequence immediately downstream of said antigenomic (+) RNA, that cleaves at the 3′ terminus of the antigenomic RNA; and (iii) a transcription termination signal for the RNA polymerase; (b) in a second container a second DNA plasmid vector comprising the following operatively linked components: (i) the bacteriophage RNA polymerase promoter; (ii) a second DNA sequence encoding an N protein of the vesiculovirus; and (iii) a second transcription termination signal for the RNA polymerase; (c) in a third container a third DNA plasmid vector comprising the following operatively linked components: (i) the bacteriophage RNA polymerase promoter; (ii) a third DNA sequence encoding a P protein of the vesiculovirus; and (iii) a third transcription termination signal for the RNA polymerase; (d) in a fourth container a fourth DNA plasmid vector comprising the following operatively linked components: (i) the bacteriophage RNA polymerase promoter; (ii) a fourth DNA sequence encoding an L protein of the vesiculovirus; and (iii) a fourth transcription termination signal for the RNA polymerase; and (e) in a fifth container a recombinant vaccinia virus comprising a sequence encoding the bacteriophage RNA polymerase. 51-74. (canceled) 